Plus One

Kerala Plus One Botany Previous Year Question Paper 2018

Time: 1 Hours
Cool off time : 10 Minutes

General Instructions to candidates :

• There is a ‘cool off time’ of 10 minutes each for Botany and Zoology in addition to the writing time ‘ of 1 hour each. Further there is a ‘ 5 minutes’ ‘preparatory time’ at the end of the Botany Examination and before the commencement of the Zoology Examination.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 4. Each carry one score. (4×1=4)

Question 1.
Fill in the blank.
In Anabaena specialized cells called…… help in nitrogen fixation.

Question 2.
There are different types of leucoplasts in plant cells. Name the leucoplast that store proteins.

Question 3.
Observe the relationship between the first two terms and fill in the blank.
Epipetalous Stamen – Brnjal
………… – Lily

Question 4.
Choose the correct answer from the bracket.
First stable product of carbon dioxide fixation in C₄ plant is ……….

(PGA, OAA, PEP, RUBP)

Answer any seven from question numbers 5 to 13. Each carries two scores. (7×2=14)

Question 5.
Match the following :

Question 6.
Complete the flowchart given below.

Question 7.
Ribosomes are organelles without a membrane found in all cells. Name another organelle devoid of membrane, seen in animal cells. Write its function

Question 8.
Plants are adversely affected by manganese toxicity. Mention the effects of manganese toxicity in plants.

Question 9.
Following figure shows the citric acid cycle

Identify the steps where FADH₂ and GTP are synthesized.

Question 10.
The given figure shows a plant belonging to liverworts. Identify the plant. Name the asexual buds seen on it and write their features.

Question 11.
State any four features of facilitated diffusion.

Question 12.
Write a note on the phenomenon plasticity exhibited by plants with an example.

Question 13.
The breakdown of glucose to pyruvic acid is called glycolysis. Where does it occur in a cell? How many ATP molecules are directly syn-thesized during this process?

Answer any four from question numbers 14 to 18. Each carries three scores.(4×3=12)

Question 14.
The tissue found between the upper and lower epidermis of a leaf is called mesophyll.
a. Write the type of cells found in this tissue in a dicot leaf.
b. Mention two differences between a dicot leaf and monocot leaf.

Question 15.
Photosynthesis is a process influenced by environmental factors as well as plant factors. Mention three factors under each category.

Question 16.
First phase of meiosis I is typically longer and complex one. Name it. Mention the five sub divisions of this phase.

Question 17.
Plant growth regulators can be employed for various agricultural and horizontal prac¬tices. Identify the growth regulators that can be used for the following purposes.
a. To have weedfree lawns
b. To increase sugarcane length
c. Fruitset in pineapples
d. Rooting in stem cuttings
e. Inhibiting seed germination
f. To promote female flowers in cucumber

Question 18.
Certain stages in cell cycle are given below. Karyokinesis, Prophase, Cytokinesis, Meta-phase, Anaphase, Telophase.
Choose the statements (from those given below) that match with these stages and prepare a table.
• Centromere split and chromosomes move to opposite poles.
• Chromosomes cluster at opposite poles and nuclear envelope assembles around.
• Chromosomes seems to be with two chromatids attached at centromere.
• Chromosomes arranged at spindle equator.
• Separation of daughter chromosomes.
• Division of cytoplasm.

Answers

Answer 1.
Heterocysts

Answer 2.
Aleuroplasts/ Proteinoplast

Answer 3.
Epiphyllous

Answer 4.
OAA

Answer 5.

Answer 6.
a. Secondary xylem
b. Metaxylem
c. Exarch
d. Stem

Answer 7.
Centrioles
Functions: Cell division, formation of basal body of flagella or cillia, spindle apparatus during cell division.

Answer 8.
• Chlorosis
• Necrosis
• Brown spots surrounded by chlorotic veins.
• Manganese competes with iron and magnesium for uptake.

Answer 9.
FADH₂ – Between the conversion of succinic acid to malic acid.
GTP -Between the conversion of α- ke- toglutaric acid to succinic acid.

Answer 10.
Plant : Marchantia ( Bryophyte)
Asexual buds : Gemma/ Gemmae
Features – Gemmae are green, multiel- lular, asexual/vegetative buds which develop in small receptacles. Gemmae become detached from the parent body and germinate to form new individuals.

Answer 11.
• Requires special membrane proteins.
• Highly selective.
• Not requires ATP energy.
• Transport saturates.
• Transport of molecules along the concentration gradient.

Answer 12.
Plants follow different pathways in response to environment or phases of life to form different kinds of structures. This ability is called plasticity.
E.g., Heterophylly in Cotton, Coriander and Larkspur etc.

Answer 13.
Glycolysis take place on cytoplasm or cytosol.
Glycolysis forms 2 ATP molecules per glucose molecule.

Answer 14.
a. Palisade parenchyma and spongy parenchyma

Answer 15.
Plant factor
Number, size, age, orientation of leaves, mesophyll cells, chloroplasts, internal C0₂ : concentration, amount of chlorophyll. External factor
Availability of sunlight, temperature, C0₂, concentration, water, availability of nutrients in the soil.

Answer 16.
Prophase I
Five sub divisions : Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.

Answer 17.
a. 2,4-D (2,4- Dichlorophenoxy acetic acid)
b. Gibberellin
c. Ethylene
d. Auxin
e. ABA /Abscisic acid
f. Ethylene / Ethephon

Answer 18.

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Model Question Paper 4

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provied.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
Which of the following sets of quantum numbers are NOT possible?

Question 2:
‘A given compound always contains exactly the same proportion of elements by weight’. Name the above law.

Question 3:
Write the general outer electronic configuration of d-block elements.

Question 4:
What is dry ice?

Question 5:
The bond order value is an important property of a molecule. How is bond order related to bond length?

Question 6:
Name the gas law which gives the relation-ship between the pressure and temperature of a fixed amount of gas at a constant volume.

Question 7:
Sodium hexametaphosphate is commercially called

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
Illustrate Markovnikov’s rule taking the example of propene.

Question 9:
Match the following by selecting the items from columns B and C which are most suitable to those in column A.

Question 10:
Write the IUPAC names of the following.

Question 11:
Consider the reaction given below:

i. Identify the major product obtained.
ii. Name the rule governing the formation of the major product.

Question 12:
The photon has a momentum as well as a wave length.
a. Which property of matter is revealed in the above statement?
b. A photon has a mass of 8.6 x 10^-30kg. Calculate its wavelength.
[Planck’s constant, h = 6.626 x 10^-34 Js]

Question 13:
Thermodynamics deals with energy changes of macroscopic systems.
a. Consider a chemical reaction taking place in a closed insulated vessel. To which type of thermodynamic system does it belong?
b. State the first law thermodynamics.

Question 14:
Mention any two similarities between Beryllium and Aluminium.

Question 15:
Analyze the following reaction:
CH₃ – CH = CH₂ + H – Br → ‘A’ + ‘B’
If ‘A’ is the major product and ‘B’ is the mi¬nor product, identify ‘A’ and ‘B’. Also name the related rule.

Question 16:
A graph of atomic radius versus atomic number is given below.

a. What do you understand from this graph?
b. Using the above graph, how will you account for the variation of ionization enthalpy in a period?

Question 17:
The threshold frequency v₀ for a metal is 6.2 x 10⁴S^-1. Calculate the K.E emitted of an electron when the radiation of frequency ν = 8.7 x 10¹⁴S^-1 strikes the metal.

Question 18:
Account for the following observations:
i. The density of ice is lower than that of water.
ii. Hard water doesn’t give ready lather with soap.

Question 19:
Represent Sawhorse and Newman projection formulae of staggered and eclipsed conformation of ethane.

Question 20:
Give the structures of the following compounds.

Answer any ten from question numbers 21 to 29. Each carries two scores.

Question 21:
A system in thermodynamics refers to that part of the universe in which observation are made.
a. What do you mean by an isolated system? Given an example.
b. Distinguish between intensive and extensive properties. Give two examples for each.

Question 22:
a. Name the species getting oxidized in the above reaction.
b. Balance the above equation by the oxidation number method.

Question 23:
The group 1 metals of the periodic table of elements are collectively called alkali metals.
a. Write the general electronic configuration of alkali metals.
b. Identify the alkali metal exhibiting anomalous properties. Explain.

Question 24:
Organic matter such as leaves, grass, trash etc. are major pollutants in water.
a. How do organic pollutants affect aquatic life?
b. What is biological oxygen demand (BOD)?

Question 25:
If the cocentration of the hydrogen ioni n a soft drink is 3 x 10^-3 M, calculate its pH.

Question 26:
Boron, Aluminium, Gallium, Indium and thallium belong to group 13 of the periodic table of elements.
a. How can you explain a higher stability of BCl₃ as compared to TlCl₃ ?
b. While Aluminium can be form the ion [AlF₆³, Boron is unable to form [BF₆ ]^3- ion. Explain.
c. State whether the compound BCl³ is acidic or basic.

Question 27:
The theory that attempts to explain the behaviour of gases is known as kinetic molecular theory.
a. On the basis of this theory, explain the compressible nature of gases and the temperature dependence on kinetic energy.
b. Liquid drops assume spherical shape. Why?

Question 28:
Neils Bohr was the first to explain quantitatively the general features of hydrogen atom structure and its spectrum.
a. Give the main postulates of Bohr’s model.
b. Find the maximum number of emission lines, when the excited electron of hydrogen atom in n = 6, drops to the ground state (n = 1).
c. Calculate the wave number of radiation due to transition of an electron from fourth orbit to second orbit. (R_H= 109677 cm^-1).

Question 29:
In the Celsius scale, melting point of ice is 0°C. Another scale of temperature is based on absolute zero.
a. Identify the scale.
b. What is the volume of a gas at absolute zero temperature?
c. Draw a graph showing the relationship between volume and temperature of an ideal gas at a constant pressure.

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
If the mass percent of the various elements of a compound is known, its empirical formula can be calculated.
a. What is mass percent? Give its mathematical expression.
b. A compound contains 4.07% hydrogen, 24.27% carbon and 71.65% chlorine. Its molecular mass is 98.96. What are the empirical and molecular formulae?

Question 31:
The IUPAC names of alkanes are based on their chain structure.
a. Give the IUPAC name of

b. Represent 1-methyl-3- propyl cyclohexane using bond line notation.
c. What is the type of hybridization of C in CH₃⁺ Also predict its shape.
d. Name the type of bond fission resulting in the formation of free radicals.

Question 32:
The group 14 elements have four electrons in the outermost shell.
a. SiCl₄ can be easily hydrolyzed by water while CCl₄ cannot be hydrolyzed. Why?
b. How are fullerenes prepared?
c. Distinguish between silicones and silicates.

Question 33:
a. Draw the structures of the following compounds.
2,3 Dilbromo-1-phenylpentane
4-Ethyl-1-fluoro-2-nitrobenzene

b. Write all possible chain isomers of the compound with molecular formula C₅H₁₂

Answers

Answer 1:
n = 2, l = 2, ml= 0, m_s =+1/2
n = 3, l = 2, ml = -3, m_s = +1/2

Answer 2:
Law of definite proportions.

Answer 3:

Answer 4:
Solid CO₂

Answer 5:

Answer 6:
Gay Lussac’s law.

Answer 7:
Calgon.

Answer 8:
According to Markovnikov’s rule, when a hydrogen halide adds to an unsymmetrical alkene, halogen atom get attached to the doubly bonded C atom containing lesser number of hydrogen atom.

Answer 9:

Answer 10:
i. 2, 2, 4 – trimethyl pentane,
ii. Hex – 4 – ene -1 – oic acid.

Answer 11:

Answer 12:
a. Dual Behaviour of matter. This means that matter possesses dual character, i.e., particle nature and wave nature.

Answer 13:
a. Isolated system.
b. First law of thermodynamics. The energy of isolated system is constant.

Answer 14:
1. Both Be and Al have strong tendency to form complex.
2. Oxides and hydroxides of both Be and Al are amphoteric.

Answer 15:

Answer 16:
a. Atomic size decreases with increase in atomic radius.
b. Ionization enthalpy increases along a period.

Answer 17:

Answer 18:
i. Hydrogen bonding gives ice an open type structure. Hence ice has lower den sity than water.
ii. Hard water contains Mg²⁺ and Ca²⁺ions.
It is due to the presence of these ions that hard water does not lather with soap.

Answer 19:
Sawhorse method.

In staggered conformation, H atoms are far apart and the repulsion is minimum. Thus staggered conformation is more stable than eclipsed conformation.

Answer 20:

Answer 21:
a. A system which can neither exchange matter nor energy with the surrounding is called isolated system, eg., hot water in a thermoflask.
b. The properties of the system which depend upon the quantity of matter are called extensive properties, eg., mass, volume.
The properties of the system which are independent of quantity of matter are called intensive properties, eg., temperature, pressure.

Answer 22:

Answer 23:
a. ns¹
b. Lithium
Anamolous properties of lithium:

• Small size
• High ionisation enthalpy
• High polarising power
• Absence of d orbitals.

Answer 24:
a. Organic pollutants decreases the amount of dissolved oxygen in water, thereby caus ing harmful effects to aquatic life.
b. The amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water is called Biochemical Oxygen Demand (BOD).

Answer 25:

Answer 26:
a. Because of inert pair effect, the +3 state of Tl is less stable. Thus BCla₃ is stable than TlCla₃. Since B is smaller than Tl it can undergo back bonding with Cl and hence BCla₃ is more stable than TlCla₃.
b. Boron does not have any d orbitals. While Al has vacant d orbitals. Thus, Al forms [AIFa₆]^3- ions while B cannot form [BF₆]^3- Hons.
c. BCla₃ is acidic because it is electron deficient and can accept electron pair.

Answer 27:
a. Gases consist of large number of identical particle. These are so small and so far a part. In kinetic theory it is considered that average K.E of gas molecules is directly proportional to the ab-solute temperature.ie as the temperature decreases, K.E of molecule decreases and intermolecular attraction between the molecule become significant. These attractive force make the molecule come closer and they become compressible.
b. Liquids assumes spherical shape due to surface tension. Liquids have tendency to minimise the surface area. Since for a sphere, surface area is minimum.

Answer 28:
a. 1. The electron in an atom revolve around the nucleus only in certain circular path called orbits.
2. The energy of the electron in a particular orbit remains constant.
3. Only those orbits are permitted in which the angular momentum of the electron is a whole number of multiple of \(\frac { h }{ 2\pi }\), where h is Plank’s constant.
4. Energy is emitted or absorbed by an atom only when an electron moves one from one orbit to another.
Maximum number of emission lines

Answer 29:

Answer 30:
a. Relative mass of each of the constituent element in 100 part of it by mass is called mass percent.

∴ Emperical formula of the compound

Answer 31:
a. 3 – ethyl-5-methylheptane

c. sp² hybridisation. Trigonal planer shape.
d. Homolytic fission.

Answer 32:
a. CCl₄ is not hydrolysed by water because carbon has no d-orbitals and hence can-not expand its co-ordination number beyond . However Si can expand its co-ordination number beyond 4 due to the availability of vacant d-orbitals. Therefore SiCl₄ readily undergoes hydrolysis.
b. Fullerenes are made by the heating of graphite in an electric arc in the presence of inert gases such as helium or argon.
c. Silicons are a group of inorganic polymers having general formula (R₂SiO)_n. The basic structural unit of silicates is SiO₄^4- units. When silicate units are linked together, they form chain, ring, sheet or three-dimensional structures.

Answer 33:

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Model Question Paper 3

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to candidates

• There is a ‘cool off-time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
•  Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
The number of protons, electrons and neutrons in a species are equal to 17, 18 and 18 respectively. Which of the following will be the proper symbol of this species?

Question 2:
One-half of the difference between the number of electrons in the bonding and antibonding molecular orbitals is called …………

Question 3:
Name the phenomenon behind clean sing action of soap.

Question 4:
Name the process used for the industrial preparation of sodium carbonate,

Question 5:
In the Lassaigne’s test for halogens, they are precipitated as ……………….

Question 6:
Write the name of any one salt responsible for the permanent hardness of water.

Question 7:
Give the IUPAC name of the following compound: CH₃ CH₂ CO CH₂ CH₂ COOH

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
Classify the following into intensive and extensive properties.
i. Internal energy
ii. Density
iii. Heat capacity
iv. Temperature.

Question 9:
Given the redox reaction:
CuO (s) + H₂ (g) → Cu (s) + H₂0 (g)
i. Identify the species which undergo reaction and which undergo oxidatlon.1
ii. Identify the reductant and oxidant in the above reaction.

Question 10:
Match the following :

Question 11:
Give the IUPAC name of the following compounds.

Question 12:
Give the name of the modified form of ideal gas equation and write down it.

Question 13:
Carbon has many allotropes.
a. Write the name of any two allotropic forms of carbon.
b. CCl₄ does not undergo hydrolysis. Give a reason.

Question 14:
i. Give the Arrhenius concept about acids and bases.
ii. Give one example each for Arrhenius acid and base.

Question 15:
When Sodium metal dissolves in liquid ammonia, it gives a deep blue coloured solution. Explain the reason.

Question 16:
A neon dioxygen mixture contains 70.6 g dioxygen and 167.5 g neon. If the pressure of the mixture of gases in the cylinder is 25 bar, what are the partial pressures of O₂ and neon in the mixture?

Question 17:
Write the difference between extensive and intensive properties. Give one example of each.

Question 18:
Fluorine reacts with ice as given below.
H₂O(s) + F₂(g) → HF (g) + HOF (g)
Justify that this is a redox reaction.

Question 19:
a. H₂O₂ is a bleaching agent. Why?
b. Complete the following reaction?
Zn (s) + NaOH (aq) → …………………..

Question 20:
Complete the following chemical reactions:

Answer any seven from question numbers 21 to 29. Each carries three scores.

Question 21:
In redox reactions, oxidation and reduction occur simultaneously.
a. How are oxidation and reduction related
to the oxidation number?
b. During a group discussion, one of your friends argues that thermal decomposition of KC/O₃ is a redox reaction while that of CaCO₃ is not a redox reaction. Give your opinion and substantiate.

Question 22:
Give the IUPAC names of the following compounds:

Question 23:
When some sodium acetate is added to a solution of acetic acid, the concentration of unionzed acetic acid increases.
a. What is the phenomenon involved? Substantiate.
b. Consider the equilibrium,

The solubility of AgCl is 1.06 x 10^-5 mol/L at 298 K. Find out its K_sp at this temperature.
c. What happens to the value of solubility and solubility product when HCI is passed through an AgCl solution?

Question 24:
Atmospheric pollution increases the global average temperature and the phenomenon is called global warming.
a. What are the major gases which contribute to wards global warming?
b. What can we do to reduce global warming?

Question 25:
The solubility product of Al(OH)₃ is 1 x 10³⁶ Calculate the solubility of Al(OH)₃

Question 26:
Account for the following :
i. Ionization enthalpy of Nitrogen is greater than that of Oxygen.
ii. 2^nd period elements show anomalous behaviour.

Question 27:
a. Give any two factors influencing the formation of an ionic bond.
b. Give the shape of the following species.
i. NH₄⁺
ii. HgCl₂

Question 28:
Redox reactions can be considered as electron transfer reactions. In an experiment a copper rod is dipped in AgNO₃ solution.
a. What happens to the colour of the solution and why?
b. Identify the oxidizing and reducing agent in this reaction.
c. Calculate the oxidation number of Cr in
K₂Cr₂O₇ and P in H₂P₂O₅.

Question 29:
a. 1-alkynes are weakly acidic in nature.
Give any two reactions to showthe acidic character of ethyne.
b. From the following, select the one in which Markownikoffs rule is best applicable.

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
The enthalpy change in a process is the same, whether the process is carried out in a Single step or in several steps.
a. Identify the law stated here. 1
b. Calculate the enthalpy of formation of CH4 from the following data:

Question 31:
a. When nitrogen and hydrogen combines to form ammonia, the ratio between the volumes of gaseous reactants and products is 1:3:2. Name the law of chemical combination illustrated here.
A compound is made up of two elements A and B, has A= 70%, B= 30%. The relative number of moles of A andB in the compound are 1.25 and 1.88 respectively. If the molecular mass of the compound is 160, find the molecular of the compound.

Question 32:
Phenol exhibit resonance.
i. Draw the resonance structures of phenol.
ii. Predict the directive influence of -OH group in Benzene ring.

Question 33:
a. Hydrogen peroxide restore the colour of lead paintings. Give a reason.
b. How does the atomic hydrogen torch function for cutting and welding purposes?

Answers

Answer 1:
\(_{ 17 }^{ 35 }{ Cl }\)

Answer 2:
Bond order

Answer 3:
Surface tension.

Answer 4:
Solvay process.

Answer 5:
Silver halides.

Answer 6:
CaCl₂ or MgSO₄

Answer 7:

Answer 8:
Extensive properties: Internal energy, Heat capacity.
Intensive properties: Density, Temperature.

Answer 9:
i. Reduction species – CuO
Oxidation species – H₂
ii. Reductant- H₂, Oxidant – CuO

Answer 10:

Answer 11:
11. i. 3 – chloropropanal
ii. 3 – methylpentanenitrite.

Answer 12:
There is deviation from ideal behaviour at high pressure and low temperaure. This is due to two faulty assumptions in kinetic theory of gases. It is corrected by van der Waal’s equation.

where n is the number of moles of the gas a and b are van der Waal’s constants.

Answer 13:
a. Diamond, graphite, fullerene
b. This is due to the absence of vacant d- orbitals in carbon.

Answer 14:
i. Acid is a substance which dissociate to give H⁺ ion in aqueous solution. Base is a substance which dissociate to give OH^– ion in aqueous solution.
ii. HCl, H₂SO₄, CH₃COOH etc are acids which give free H⁺ ions in aqueous solution.

Answer 15:
Blue colour H₂ gas is evolved during the process. If M is alkali metal.

Blue colour due to the ammoniated electron which absorbs energy.

Answer 16:

Answer 17:
Extensive – Depends on the quantity of matter, eg., internal energy, heat capacity enthalpy volume, mass etc.
Intensive – Does not depend on the quantity of matter, eg., Density, S.T.P, T, etc.

Answer 18:
Oxidation number of fluorine decreases in HF while the oxidation no. of fluorine in-creases in HOF. So it is a redox reaction.

Answer 19:
a. H₂O₂ decomposes to release nascent oxygen that oxidises the colouring matter to colourless.
b. Zn(s)+2NaOH(aq) → Na₂ZnO₂(aq) +H₂(q)

Answer 20:

Answer 21:
a.Oxidation is a process which involves an increase in oxidation number of an element.
Reduction is a process which involves a decrease in oxidation number of an element.
IMG
The reaction (1) is a redox reaction because there is a change in oxidation state. But (2) is not a redox reaction because there is no change in oxidation state.

Answer 22:
a. 5, 5 -dimethyl heptan – 2 – ol
b. 2 – pentanone
c. 2, 4, 6 – tribromophenol.

Answer 23:
a. Common ion effect. It the suppression of dissociation of weak electrolyte
(CH₃COOH) by addition of a salt containing common ion (CH₃COONa).
IMG
c. When HCI gas is passed through AgCl solution. Solubility of AgCI decreases while the solubility product does not change.

Answer 24:
a. CO₂, methane, chlorofluoro carbons etc are the major gases which contribute to- wards global warming.
b. 1. Minimise the use of automobiles.
2. Plant more trees.
3. Avoid burning of dry leaves, wood.

Answer 25:

Answer 26:
i. because of the half filled electronic configuration of N. (N = 1s² 2s² 2p³)
ii. due to their small size, high electrone gativity and ionisation enthalpy,large charge/radius ratio and due to the absence of vacant d-orbitals.

Answer 27:
a. Low ionisation enthalpy of the electropositive atom (metal atom).
High negative electron gain enthalpy of the electronegative atom (non-metal atom)
High lattice enthalpy of the ionic compound formed.
i. NH⁴⁺ – Tetrahedral
ii. HgCl² – Linear

Answer 28:
a. The solution becomes blue colour due to the formation of Cu²⁺ ions.
b. Ag⁺ (AgNO₃) is the oxidising agent and Cu is the reducing agent.
c. Oxidation number of Cr in K₂Cr₂O₇ is +6 and P in H₂P₂O₅ is +4.

Answer 29:
a. Ethyne reacts with sodium ethynide and liberate H₂. It reacts with sodamide (NaNH₂) to form sodium ethynide and liberate ammonia.

Answer 30:

Answer 31:
a. Gay – Lussac’s law of Gaseous volumes
b. The relative number of moles means % / atomic mass

Element	%	Relative no.of moles	Simple ratio	Simplest whole no.ratio
A	70	1.25	1.25/1.25= 1	2
B	30	1.88	1.88/1.25 = 1.5	3

Empirical formula is A₂B₂
Atomic mass of A = % / no.of moles = 70 / 1.25 = 56
Atomic mass of B = % / no.of moles = 30/ 1.88 = 15.96
So, emp. Formula mass = 56 x 2 + 15.96 x 3 = 159.88 = 160
n = mol. mass / emp.Formula mass = 160/160 = 1
Molecular formula = (emp.Formula)n = (A₂B₃)X 1 = A₂B₃

Answer 32:

ii. -OH group is an ortho-para directing group.

Answer 33:
a. This is due to the oxidising action of H₂O₂.

b. Here H atoms are allowed to recombine on the surface to be welded to generate the temperature of 4000K.

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Model Question Paper 2

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to candidates

•  There is a ‘cool off time’ of 15 minutes in addition to the writing time.
•  Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provied.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
The ozone in the stratosphere is destroyed by

Question 2:
The geometry of SF₆ molecule is …………
i. tetrahedral
ii. planar
iii. octahedral
iv. triagonal bipyramidal

Question 3:
Syn gas is a mixture of …….
i. CO and H₂O
ii. CO and H₂
iii. CO₂ and H₂
iv. CH₄ and CO

Question 4:
Representation of orbital with quantum numbers n = 3, l = 1 is ………….

Question 5:
The metal present in the chlorophyll of plants ¡s …………

Question 6:
Thermodynamically, the most stable allot rope of carbon is ………..

Question 7:
The atomic number of the element with IUPAC nane Ununbium is ……….

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
Explain sp³ hybridisation taking methane (CH₄) as an example.

Question 9:
Write the IUPAC name of the following compounds:

Question 10:
The Taj Mahal in India has been affected by ‘acid rain’. Explain the causes and harmful effects of acid rain.

Question 11:
Calculate the number of molecules in each of the following:
i. 1 g N₂
ii. 1 g CO₂
(Given that N_A is 6.02 x 10²³, molecular mass of N₂ is 28 and CO₂is 44).

Question 12:
a. How many moles of dioxygen are present in 64 g of dioxygen (Molecular mass of dioxygen is 32).

b. The following data were obtained when dinitrogen (N₂) and dioxygen (O₂) react together to form different compounds.

Question 13:
a. The number of electrons, protons and neutrons in a species are equal to 18,16 and 16 respectively. Assign the proper symbol to the species.

b. Among the following electronic configurations, which one is correct?

Question 14:
Give reasons:
i. KO₂ is paramagnetic.
ii. Solutions of alkali metals in liquid ammonia are blue in colour.

Question 15:
An alkene ‘A’ on ozonolysis gave two molecules of formaldehyde. Write the name of ‘A’ and the chemical equation of ozonolysis.

Question 16:
Photoelectric effect was first observed by Hertz.

1.  The number of electrons ejected in the photoelectric effect is proportional to ……….. of light used. [Frequency, intensity]
2. Select the correct statement related to the photoelectric effect:
   • Threshold frequency is the maximum frequency required to cause photoelectric emission from a particular metal.
   • The kinetic energy of the photoelectrons is directly proportional to the frequency of incident light.
   • Work function is the same for all metals.

Question 17:
Le Chatelier’s principle helps to explain the effect of change in conditions on equilibrium.
Discuss the effect of pressure in the following equilibrium on the basis of Le Chatelier’s principle:

Question 18:
Analyse the following graph between ionization enthalpy and atomic number.

What do you observe from the graph? Give justification for your observation.

Question 19:
Carbocations are formed by the heterolytic cleavage of a covalent bond.
a. What is heterolytic bond fission?
b. Arrange the following carbocations in the increasing order of stability:

Question 20:
Balance the following equation by the half-reaction method.

Answer any seven from question numbers 21 to 29. Each carries three scores.

Question 21:
Two important oxides of carbon are carbon monoxide and carbon dioxide.
a. Why is CO called a poisonous gas?
b. How is CO₂ responsible for global warming?
c. What are producer gas and water gas? Mention their uses.

Question 22:
Complete the following reactions:

Question 23:
Hybridization influences the bond length and bond enthalpy in organic compounds:
a. Compare the bond length and bond strength of C-H bonds formed by sp and sp₃ hybridized carbon atoms. Give reason.
b. How many s and p bonds are present in the following molecules?
i. CH₃ – CH₂ – CH₃
ii. CH₃ – C = CH

Question 24:
Particulate pollutants are the minute solid particles or liquid droplets in air.
a. Suggest two examples for non-viable particulate pollutants.
b. Write any two adverse effects of photochemical smog.

Question 25:
The behaviour of acids and bases can be explained using different concepts.
a. Select the Lewis acid from the following:
(NH₃, OH^–, BCl₃, Cl^–)
b. What are conjugate acid-base pairs? illustrate using a suitable example.

Question 26:
Valence Bond Theory(VBT) and Mole-cular Orbital Theory (MOT) are the two important theories of chemical bonding.
a. Out of the following, which is the hybridization of phosphorus in PCl₅?
(sp², sp³, dsp², sp²d)
b. Explain the geometry of the PCl₅ molecule and account for its high reactivity.

Question 27:
Free rotation is possible with respect to a C – C bond in the case of alkanes.
a. The repulsive interaction between the adjacent bonds in a conformation is called ………
b. Draw Newman’s projections of the two conformers of ethane. Which among these is more stable? Justify.

Question 28:
Equilibrium is possible only in a closed system at a given temperature.
a. Write the expression for equilibrium constant, K_c^– for the reaction.
4NH_3(g) +5O_2(g) ⇌ 4NO_(g) + 6H₂O_(g)
b. What happens to the value of the equilibrium constant (Kc) when the above reaction is reversed?

Question 29:
a. What is the number of hydrogen atoms in 1 mole of methane (CH₄)?
b. Calculate the amount of carbon dioxide formed by the complete combustion of 80g of methane as per the reactions
CH_4(g) + 2O_2(g) → CO_2(g) + 2H₂ O_(g)
(Atomic masses: C= 12.01u, H= 1.008u, O = 16u).

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
The Valence Shell Electron Pair Repulsion (VSEPR) theory helps in predicting the shapes of covalent molecules.
a. Arrange the bond pair electron and lone pair electron in the decreasing order of the repulsive interactions among them.
b. A molecule of the type. AB₃E₂ has three bond pairs and two lone pairs of electrons. Predict the most stable arrangement of electronpairs in this molecule.
c. The bond order value is an important property of a molecule. How is bond order related to bond length?
d. Write the electronic configuration of an oxygen molecule and justify its magnetic nature.

Question 31:
Most of the naturally occuring processes are spontaneous.
a. Give the criteria for spontaneity of a process in terms of free energy change (∆G).
b. Exothermic reactions associated with a decrease in entropy are spontaneous at lower temperatures. Justify on the basis of Gibbs equation.
c. Find the temperature above which the reaction.
MgO_s + C_s → Mg_s + CO_(g)
becomes spontaneous. (Given ∆H° = 490 KJ mol^-1 and ∆S° = 198JK mol^-1)

Question 32:
What do you mean by the following terms?
a. Homolytic fission
b. Heterolytic fission
c. Nucleophiles
d. Electrophiles

Question 33:
The gases which obey Gas Laws at all temperatures and pressures are called ideal gases.
a. Give reasons for the deviation of real gases from the ideal gas behaviour.
b. Calculate the minimum pressure required to compress 500 ml of air at 1 atm to 300 ml at the same temperature.

Answers

Answer 1:
Cl
Answer 2:
Octahedral

Answer 3:
CO and H₂

Answer 4:
3p

Answer 5:
Magnesium

Answer 6:
graphite

Answer 7:
112

Answer 8:
i. It is defined as the phenomenon of inter-mixing of pure atomic orbitals of slightly different energies and shapes to form new hybrid orbitals of equivalent energies and identical shapes.
ii. Electronic configuration of C (6) is 1s² 2s² 2p_x¹ 2p_y¹ in ground state. It has electronic configuration 1s2 2s1 2px1 2py1 2pz1 in excited state (since C is tetravalent only in excited state).

Answer 9:
a. pent – 4 – ene – 2 – ol
b. 2, 5 – dimethylheptane

Answer 10:
Due to acid rain caused from exhaust of industries the marble layers of Taj Mahal get destroyed. Acid rain is caused by of acid ox-ides such as oxides of sulphur and nitrogen in the air.
Acid rain destroys crops, aquatic lives and buildings. The acid rain will carrode build ing material like marble, limestone etc. and dissolve heavy metals like Cu,Pb,Hg, etc. in water and make it unfit for drinking. It fades the colour of fabrics, leather and paper.

Answer 11:
i. Number of molecules present in 1g of
N² = 6.02 x 10²³/28 = 0.215 x 10²³
ii. Number of molecules present in 1 g of CO₂ = 6.02 x 10²³/44 = 0.136 x 10²³

Answer 12:
a. No. of moles = 64/32 = 2 mole
b. Law of multiple proportions.

Answer 13:
\(_{ 16 }^{ 32 }{ { S }^{ 2- } }\)
b. fig (iii) is the correct one. fig(i) and fig(ii) do not obey Hund’s rule.

Answer 14:
i. Presence of one unpaired e’.
ii. Due to ammoniated electrons.

Answer 15:

Answer 16:
a. Intensity.
b. Kinetic energy of the photoelectrons is directly proportional to the frequency of incident light.

Answer 17:

The forward reaction involves a decrease in number of molecules. Hence a high pressure favours forward reaction (formation of products).

Answer 18:
The graph shows variation of ionisation enthalpy along a group.
Moving down the group, atomic size increases and the outer electrons are far away from the nucleus. There is also an increase in the screening of nuclear charge by electron in inner shells. As a result the removal of electrons becomes easier down the group and ionization enthalpy decreases.

Answer 19:
a. When a bond between 2 atoms breaks in such a way that the shared pair of electrons stays on any one of the atoms. The process is called hetrolytic fission.

Answer 20:

Answer 21:
a. Carbon monoxide reacts with haemo globin to form carboxy haemoglobin which is highly stable complex. This prevent haemoglobin in red blood cells from carrying oxygen and ultimately resulting in death. Hence CO is considered as poisonous gas.
b. CO absorbs IR radiations. This lead to increase in green house effect and thereby raising the temperature of the atmosphere.
c. The mixture of CO and H₂ is called water gas. The mixture of CO and N₂ is called producer gas. Both water gas and pro ducer gas are very important industrial fuels.

Answer 22:

Answer 23:
a. Bond length of C-H bond for sp hybridised carbon is less and that of sp³ hybridised carbon is high. Bond strength is greater for C-H bond is sp hybridised carbon than that for sp³ hybridised carbon.
b. 1.10 σ bonds.
2. 6 σ bonds and 2 π bonds.

Answer 24:
a. Mist, smoke, dust
b. *Causes irritation to eyes.
*Causes health problems like head ache, chest pain, dryness of throat, cough and difficulty in breathing.
*PAN adversely affects green plants.

Answer 25:
a. BCl₃
b. The acid-base pair which is formed from each other by loss or gain of proton is called as conjugate acid-base pairs. Consider the reaction,

Water act as a base since it accepts proton. HCl act as an acid since it donate proton.
Cl^– is the conjugate base of acid HCl.
H₃O⁺ is the conjugate acid of base H₂O.

Answer 26:

In PCl₅, 5 sp³ d orbitals of phosphorus over¬lap with singly occupied P orbitals of chlorine atoms to form 5 P-Cl bonds. Three P- C/ bond lie in one plane and make bond angle of 120°. These bonds are equitorial bonds. The remaining 2 P-Cl bond lie above and below the equitorial plane making an angle of 90° with the plane. These bonds are called axial bonds. Axial bonds are longer and weaker than equitorial bonds since they suffer more repulsive interactions from equitorial bond pairs. As a result PCl₅ is highly reactive.

Answer 27:
a. Torsional strain.
b. Newman’s projection

Staggered conformation is more stable than eclipsed conformation. This is because in staggered conformation, the hydrogen atoms are at maximum distance apart and there is minimum repulsion and it is more stable. But in eclipsed conformation, H atoms of one carbon atom are directly behind those of other and thus repulsion is maximum and hence least stable.

Answer 28:

Answer 29:
a. 4 moles of hydrogen or 4 x 6.023 x 10²³ atoms of hydrogen.
b. According to the equation, 1 mole CH₄ gives 1 mole CO₂ number of moles of methane = \(\frac { 80 }{ 16 }\)
= 5 moles \ 5 moles of CO₂ is formed, ie., 5 x 44 = 220g CO₂

Answer 30:
a. Lone pair – lone pair > lone pair – bond pair > bond pair – bond pair.

Answer 31:
a. ∆G = ∆H – T∆S
When ∆G is negative (∆G < 0), the pro-cess is spontaneous, b. For exothermic reactions, ∆H = -ve and ∆S = -ve When ∆H = -ve, ∆S = -ve, ∆G become -ve only. When ∆H >T∆S. Such reactions are spontaneous only at low temperature.

The reaction is spontaneous above this temperature.

Answer 32:
a. When the bond between two atoms A-B breaks in such a way that each fragment carries one unpaired electron, the process is called homolytic fission,
b. When the bond between two atoms A-B breaks in such a way that the shared pair of electrons stays on any one of the atoms, the process is called heterolytic fission.
c. Electron rich species are called nucleo-philes, (nucleus loving). They has attraction for a positively charge centre.
eg:, OH^–, CN^–, I^–
d. These are the reagents which attacks electron rich centres in the substrate.

Answer 33:
a. Two postulates of kinetic theory of gases are defective:

i. Volume occupied by gas molecule is negligible as compared to the total volume of the gas.
ii. The force of attraction and repulsion among the gas molecule are negligible.

At low temperature and high pressure, gas is in compressed states. But molecules are incompressible. As a result the volume of the molecules in the gas cannot be ignored in comparison to the volume occupied by gas.
At low temperature and high pressure, the volume of the gas becomes small, and molecules come closer to each other. Under these conditions, the at¬tractive force between the molecules become operative. Hence under these conditions real gas deviate from ideal behaviour.

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Model Question Paper 1

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provied.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
Give the equation showing relation between empirical formula and molecular formula of a compound.

Question 2:
Which of the following transition of electron in the hydrogen atom will emit maximum energy ?
i. n₅ → n₄
ii. n₄ → n₃
iii. n₃ → n₂
iv. same in all transition

Question 3:
The geometry and type of hybridisation of central atom in BF₃ are
i. linear, SP
ii. tetrahedral, SP³
iii. trigonal planar,SP²
iv. Pyramidal, SP³

Question 4:
Arrange the following elements in the increasing order of first ionisation energy: Li, Be,B

Question 5:
The compressibility factor of an ideal gas is …………

Question 6:
What is the molecular formula of Buck ministers fullerene ?

Question 7:
Ozone layer depletion in Antarctica is due to the formation of the compound
i. acrolein
ii. formaldehyde
iii. SO₂ and SO₃
iv. chlorine nitrate

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
In the two oxides of carbon, the mass ratio of oxygen is 1.33 : 2.66. Identify the law illustrated by the above ratio and state the law.

Question 9:
Using s, p, d notation describe the orbitals with following set of quantum number.

Question 10:
A set of molecules are given below:
NaCl, O₂, KCl, BF₃, PCl₅
a. Classify the molecules into ionic and covalent compounds.
b. Classify the above molecules into those obeying octet rule and those not obeying octet rule.

Question 11:
Identify the extensive and intensive properties from the following :
density, internal energy, heat capacity, molar heat capacity

Question 12:
Match the following:

Question 13:
Derive the relation between Kp and Kc of a gaseous reversible reaction.

Question 14:
a. What is Buffer solution ?
b. How a basic buffer can be prepared ?

Question 15:
Briefly explain the bonding in diborane.

Question 16:
Nitrogen, sulfur, halogen and phosphorous present in an organic compound are detected by Lassaigne’s test. Explain Lass aignes test for detecting nitrogen?

Question 17:
Write Van der Waals equation for one-mole gas and also write the physical significance of Van der Waals constants,

Question 18:
Complete the reaction.

Question 19:
Predict the products formed by addition reaction of HBr to but -1- ene in the presence of peroxide and in the absence of peroxide.

Question 20:
Give any two importance of green chemistry in day-to-day life.

Answer any seven from question numbers 21 to 29. Each carries three scores.

Question 21:
Calculate the number of atoms in each of the following.
a. 14 g of Nitrogen (N₂).
b. 14 mole atom Nitrogen (N₂)
c. 14 U of Nitrogen (N₂).

Question 22:
a. Identify the position of the elements in the periodic table having outer electronic configuration.
i. ns²np⁴ with n = 3
ii. (n-1)d² ns² with n=4.
b. “Removal of electron from an atom become easier on moving down the group.” Give reason.

Question 23:
a. Write the two postulates of Kinetic molecular theory of gases responsible for deviation of real gases from ideal behaviour.
b. What is Boyle point ?

Question 24:
a. Derive the equaion for Gibbs energy change (∆G ) in terms of ∆H and ∆S.
b. Write any two condition for which G becomes negative according to Gibbs equation.

Question 25:
Decomposition of PC15 can be represented as
PCl_5(g) → PCl_3(g)+ Cl_2(g)

∆H = 124.0KJmol^-1
Describe the effect of the following on the above equilibrium ?
a. addition of PCl₅
b. increase in pressure.
c. increase in temperature

Question 26:
Explain the following reactions.
a. CO is heated with ZnO
b. Boric acid is added to water
c. BF₃ with NaH.

Question 27:
Balance the following redox reaction using oxidation number or ion-electron method :

Question 28:
What causes the temporary and permanent hardness of water ? Give one method to remove permanent hardness ?

Question 29:
Analyze the given compound.
C₂H₅C(CH₃) = C(CH₃)C₂H₅
a. Write the IUPAC name of the compound.
b. Draw the structures of the geometrical isomers possible for the compound.

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
a. Write the Schrodinger wave equation and explain the terms.
b. Draw the boundary surface diagrams of any four 3d orbitals.

Question 31:
Compare the relative stability of the following species and indicate their magnetic properties based on molecular orbital theory.
O₂^– and O₂⁺

Question 32:
By passing Cl₂ gas through a solution, gets bleaching powder
a. Write the balanced chemical equation for above reaction.
b. What happens if CO₂ gas is passed instead of Cl₂ and write the balanced chemical equation.

Question 33:
Which of the following carbocation is most stable ?
(CH₃)₃C⁺, (CH₃)₂CH⁺, CH₃CH₂CH₂⁺
Justify your answer
b. Write the principle involved in the distillation of organic compound under reduced pressure ? Give an example.

Answers

Answer 1:
Relation between empirical and molecular formula,
MF = (EF) x n
Where n is a simple whole number

Answer 2:
n₃ → n₂

Answer 3:
Triagonal planar, SP²

Answer 4:
Be > B > Li

Answer 5:
The deviation from ideal behaviour is measured in terms of compressibility factor Z, which is the ratio of product PV and nRT.

Answer 6:
C₆₀

Answer 7:
Chlorine nitrate

Answer 8:
Law of Multiple Proortions
According to this law, if two elements can combine to form more than one compound the masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers.

Answer 9:
a. 4P
b. 3d

Answer 10:
a. lonic : NaCl, KCl
Covalent: BF₃, PCl₅₃, O₂
b. Obeying octet rule – NaCl, KCl, O₂
Not obeying Octet rule : BF₃, PCl₅

Answer 11:
Extensive : Heat capacity, Internal energy
Intensive : density, molar heat capacity

Answer 12:

Answer 13:
K_p = K_c (RT)^∆n

Answer 14:
a. The solutions which resist change in pH on dilution or with the addition of small amounts of acid or alkali are called Buffer Solutions.
b. Basic buffer : Buffer mixture of a weak base and its salt with a strong acid,
e.g., NH₄OH and NH₄Cl (pH = 9.25)

Answer 15:

In boron atom lies one plane. Above and below this plane, there are 2 bridging H- atom. Each bridged H atom is bonded to 2 boron atom only by sharing of 2 electrons. Such a bond is called 3 centered 2 electron bond. Thus diborane have two (B-H-B) bonds, ie., two 3-centered 2 electron bond and four (B-H) bonds, ie., four 2 centered 2 electron bond.

Answer 16:
By fusing organic compound with sodium metal, the elements present in the compound forms corresponding water soluble salts.

Detection of Nitrogen:
N exist as NaCN in sodium fusion extract.

On heating with con.H₂SO₄, Fe²⁺ oxidised to Fe³⁺ to give prussion blue in colour.

Detection of Halogens:
Halogen exist as halides (max.) in fusion extract. Mien AgNO₃ and HNO₃ is added they form AgX.
X^– + Ag⁺ AgX; (X = Cl, Br, I)
AgCl – white ppt
Agl – yellow ppt
AgBr – pale yellow

Detection of Suphur:
Sulphur as Na2S is fusion extract when sodium nitroprusside added gives violet colour.
Na₂S + Na₂[Fe(CN)₅N0)] → Na₄[Fe(CN)₅ NOS] (violet colour)

Detection of Phosphorus:
The compound is heated with oxidising reagent (Sodium peroxide). The phosphorous present in the compound is oxidised to phosphate. The solution is boiled with nitric acid and then treated with ammonium molybdate. A yellow colouration or precipitate indicates the presence of phosphorus.

Answer 17:
There is deviation from ideal behaviour at high pressure and low temperaure. This is due to two faulty assumptions in kinetic theory of gases. It is corrected by van der Waal’s equation.

where n is the number of moles of the gas a and b are van der Waal’s constants.

Answer 18:

Answer 19:

Answer 20:
Dry cleaning of clothes. Tetra chloro ethene (Toxic and contaminates ground water) which is used as solvent for dry cleaning is replaced by liquified CO₂.
• Bleaching of paper. Cl₂ gas is replaced H₂O₂.
• Synthesis of chemicals.

Answer 21:

Answer 22:
i. 1s² 2s² 2p⁶ 3s² 3p⁴
Block – p block
Atomic number – 16
Group – 16th group
Period – 3
Element – Sulphur

ii. 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²
Block – d block
Atomic number – 22
Group – 4 th group
Period – 4
Element – Ti

b. Down a group, the outermost electron being increasingly farther from the nucleus, there is an increased shielding of the nuclear charge by the electrons in the inner levels. In this case increase in shielding out weights the increasing nuclear charge and the removal of the outermost electrons requires less energy down a group.

Answer 23:
a. Maxwell, Boltzmann and others put forward a theoretical model of the gas. The theory is known as kinetic molecular theory of gases or microcopic model of gases.

Postulates of kinetic molecular theory are:
• All gases are made up of a large number of extremely small particles called molecules.
• The molecules are separated from one another by large distances so that the actual volume of the molecules is negligible as compared to the total volume of gas.
• The molecules are in a state of continuous rapid motion in all directions. During their motion, they keep on colliding with one another and also with the walls of the container.

b. The temperature at which a real gas obeys ideal gas law over an appreciable range of pressure is called Boyle temperature or Boyle point.

Answer 24:
a. Neither decrease in enthalpy nor increase in entropy alone can determine the direction of spontaneous hange for these systems. For this purposes, we define a new thermodynamic function the Gibbs energy or Gibbs function, G as
G = H – TS
The change in Gibbs energy for the system
∆G_sys = ∆H_sys – T∆S_sys – S_sys ∆T
At constant temperature, ∆T = 0
∆G_sys = ∆H_sys

Usually the subscript ‘ system’ is dropped and we simply write this equation as
∆G = ∆H – T∆S
Gibbs energy change = enthalpy change – temperature x entropy change.
It is reffered to as the Gibbs equation.
b. 1. ∆G is always -ve for a spontaneous process.
2. ∆G became negative for a reactions which are spontaneous only at a low temperature.

Answer 25:
a. Shift the equilibrium in the forward reaction
b. Increase of pressure shift the equilibrium towards left (backward direction) where then no.of particle is less.
c. Increasing temperature shift the equilibrium in the forward direction as it is endothermic.

Answer 26:
a. ZnO(s) + CO (g) \(\underrightarrow { \Delta }\) Zn(s) + C0₂
Extraction of metals

b. When boric acid is added to water, it accepts electrons from -OH ion. Boric acid is sparingly soluble in cold water i however fairly soluble in hot water, boric acid behaves as a weak monobasic acid. It doesn’t act as proton donor, beh- 0 aves as a lewis acid, it accepts a pair of electrons.
B(OH)₃ + 2HOH → [B(OH)₄]^– + H₃O⁺
450 A:
c. 2BF₃ + 6 NaH \(\underrightarrow { 450K }\) B₂H₆ + 6 NaF
Diborane is produced on an industrial scale by the reaction of BF₃ with sodium hydride.

Answer 27:

Answer 28:
Temporary hardness is due to presence of bicarbonates of Ca and Mg in water. Permanent hardness is due to presence of chlorides and sulphates of Ca and Mg in water. Permanent hardness re¬moved by ion exchange method or permutit process (Zeolite).

Answer 29:

Answer 30:
a. Erwin Schrodinger developed an atomic model taking into account both the wave and particle nature of elecron. This equation is known as shrodinger wave equation. For a system the schrodinger equation is written as
H\(\Psi\) = E\(\Psi\), where h is a mathematical operatior called Hamiltonian. Schrodinger gave a recipe of constructing this operator from the expression for the total energy of the system. The total energy of the system takes into accountthe kinetic energiesofallthe subatomic particles attractive potential bet-ween the electrons and nuclei and repuisive potential among the electrons and nuclei individually. Solution of this equation gives E and \(\Psi\).

Answer 31:

Answer 32:
a. 2Ca(OH)₂ + 2Cl₂ → CaCl₂ + Ca(OCl)₂ + 2H₂O Bleaching powder
b. When CO₂ is passed through lime water Ca(OH)₂ it turns milky due to the formation of calcium carbonate.
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

Answer 33:
a. (CH₃)C⁺ >(CH₃)₂CH₊ > CH₃CH₂CH₂⁺

Carbocations are classified as primary, secondary or tertiary. Its stability follows the order 3° > 2° > 1° due to inductive effect and hyperconjugation.
b. This method is used to purify liquids having very high boiling points and those, which decompose at or below their boiling points. Such liquids are made to boil at a temperature lower than their normal boiling points by reducing the pressure on their surface. The pressure is reduced with the help of a water pump or vacuum pump.

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Improvement Question Paper 2018

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to Candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provied.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
Name the type of smog generally formed during cool and humid climate.

Question 2:
Predict the shape of XeF₄ molecule, according to VSEPR theory.

Question 3:
Which is the acidic oxide among the following?

Question 4:
How many angular nodes are present in a 5f-orbital?

Question 5:
The allotrope of carbon with the highest thermodynamic stability is …………

Question 6:
The critical temperatures of some gases are given in the following table:


Question 7:
The number of oxygen atoms present in 5 moles of glucose (C₆H₁₂O₆) is ……….

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
By using the concept of hybridization, explain the structure of H₂O molecule.

Question 9:
Give the IUPAC names of the following compounds.

Question 10:
Write any two applications of green chemistry in day-to-day life.

Question 11:
Explain the effects of temperature and pressure on the following equilibrium.

Question 12:
Draw the structure of orthoboric acid. Why it is not a protonic acid?

Question 13:
Find the molecular formula of the compound with molar mass, 78g mol^-1, and empirical formula CH.

Question 14:
What is meant by entropy of a system? What happens to the entropy during the following changes?

Question 15:
Represent graphically, the variation of prob-ability density (\({ \Psi }^{ 2 }\) (r )) as a function of distance (r) of the electron from the nucleus for 1s and 2s orbitals.

Question 16:
Derive an equation relating molar mass of an ideal gas with its density.

Question 17:
What is Wurts reaction? Give an example.

Question 18:
Define buffer solutions and write one example for an acidic buffer.

Question 19:
Cycloheptatrienyl Cation is given below :

Is this ion aromatic or not? Justify the answer.

Question 20:
Write the thermochemical equation corresponding to the standard enthalpy of formation of benzene.
Hint: ∆_f H^\(\Theta\) of benzene = +49.0 Kjmol^-1

Answer any seven from question numbers 21 to 29. Each carries three scores.

Question 21:
Justify the following:
a. ‘Ne’ has positive value for electron gain enthalpy.
b. The electron gain enthalpy of ‘F’ is lower than that of ‘Cl’.
c. The size of ‘Al³⁺’ is lower than that of F.

Question 22:
Identify X, Y and Z in the following sequence of reactions :

Question 23:
Calculate the mass of oxalic acid dihydrate (H₇C₂O₄.2H₂O) required to prepare 0.1M, 250 ml of its aqueous solution.

Question 24:
Balance the following Redox reaction by the ion-electron method or oxidation number method (Acid medium)

Question 25:
Explain any one method of preparation and structure of diborane.

Question 26:
The value of the equilibrium constant is useful to predict the extent of reaction and the direction of the reaction at a given stage. Explain.

Question 27:
Give a reason for the following :
a. H₂O₂ is stored in wax-lined glass or plastic vessels in dark.
b. Hard water is not suitable for laundry.

Question 28:
Calculate the total pressure in a mixture of 3.5 g of dinitrogen and 16 g of dioxygen confined in a vessel of 2 dm³ at 27°C. (R=0.083 bar dm³K^-1 mol^-1).

Question 29:
The reaction of cyanamide (NH₂CN) with dioxygen was carried out in a bomb calorimeter and AM was found to be -742.7kJ mol^-1, at 298 K. Calculate enthalpy change for the reaction at 298 K.

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
Write the molecular orbital electronic configurations of N₂ and O₂ and calculate their bond orders. Give a comparison of their stability and magnetic behavior.

Question 31:
Briefly describe the principles of the following techniques, taking an example in each case.
a. Crystallization
b. Simple distillation
c. Distillation under reduced pressure
d. Paper chromatography

Question 32:
Give the postulates of Bohr model of hydrogenatom. Also write two merits and two limitations of this model.

Question 33:
Account for the following :
a. Blue coloured solutions are obtained when alkali metals are dissolved in liquid ammonia.
b. ‘Li’and ‘Mg’ show similar properties.
c. Aqueous solution of Na₂CO₃ is alkaline.
d. BeS0₄ and MgSO₄ are readily soluble in water.

Answers

Answer 1:
Classical smog

Answer 2:
Square planar

Answer 3:
a. Cl207

Answer 4:
3

Answer 5:
Graphite

Answer 6:
O₂

Answer 7:
5 mole glucose contains 30 moles oxygen.
So the number of Oxygen atoms present in 5 moles of glucose = 30 x 6.022 x 10²³

Answer 8:

The shape should have been tetrahedral if there were all bp but two Ip are present so the shape is distorted tetrahedral or angular. The reason is Ip-Ip repulsion is more than Ip- bp repulsion which is more than bp-bp repulsion. Thus, the angle is reduced to 104.5° from 109.5°

Answer 9:
a. 3 – Ethyl – 1,1 – dimethylcyclohexane
b. 3 – Bromo – 3 – chloroheptane

Answer 10:

• Dry cleaning of clothes. Tetrachloroethene
(Toxic and contaminates groundwater)
which is used as a solvent for dry cleaning is replaced by liquified CO₂.
• Bleaching of paper. Cl₂ gas is replaced H₂O₂.
• Synthesis of chemicals.

Answer 11:
Low temperature favours forward reaction.
High pressure favours forward reaction.

Answer 12:

Protonic acid are those acids which ionizes in solution and produce protons . But Boric Acid/orthoboric acid is monobasic and a weak acid. It doesn’t donating proton it accepts electrons of OH- which produces due to ionisation of water into H + and OH- hence we can say it act as a lewis acid and proton is remove from water instead of boric acid.

Answer 13:
The empirical formula of the compound = CH
Empirical formula mass =12 x 1 + 1 x 1 = 13
Molar mass = 78

Answer 14:
Measure of degree of disorders or randomness of a system.
a. Entropy decreases
b. Entropy increases

Answer 15:

Answer 16:
Ideal gas equation can be rearranged as follows:
\(\frac { n }{ V }\) = \(\frac { P }{ RT }\)
Replacing n by \(\frac { m }{ M }\)
\(\frac { m }{ MV }\) = \(\frac { P }{ RT }\)
We get \(\frac { d }{ M }\) = \(\frac { P }{ RT }\) ; where d is the density.
On rearranging equation we get the rela-tionship for calculating the molar mass of a gas.
M = \(\frac { dRT }{ P }\)

Answer 17:
Alkyl halides on treatment with sodium metal in dry ethereal (free from moisture) solution give higher alkanes. This reaction is known as Wurtz reaction and is used for the preparation of higher alkanes containing even number of carbon atoms.

Answer 18:
A buffer solution is one which can resist change in its pH value on the addition of small quantities of acid or base.
Example for acidic buffer is blood.

Answer 19:
Yes. It is aromatic. In the case of cycloheptatriene, there are seven carbon atoms. Except one carbon (one is in sp³ hybrid state), all are in sp² hybrid state and each has an unhybridized pure p orbital perpendicular to the molecular plane, in the case of cycloheptatrienyl cation contains 6 π electrons, fulfilling the Huckle rule and the carbocation also in sp² hybrid state leads continuous delocalization. Hence it is aromatic.

Answer 20:
6C_(s) + 3H_2(g) → C₆H₆ (I); ∆_f H^\(\Theta\) = + 49 kJ/mol

Answer 21:
a. Noble gases have large positive electron gain enthalpies because the electron has to enter the next higher principal quantum level leading to a very un stable electronic configuration. It may be noted that electron gain enthalpies have large negative values toward the upper right of the periodic table preceding the noble gases.
b. Electron gain enthalpy of F is less negative than that of the succeeding element This is because when an electron is added to F, the added electron goes to the smaller n = 2 quantum level and j suffers significant repulsion from the i other electrons present in this level. For the n = 3 quantum level ( Cl), the ; added electron occupies a larger > region of space and the electron-electron repulsion is much less.
c. For iso electronic species, size of ion decreases with increase in nuclear charge atomic number or cation has a smaller size than anion.

Answer 22:

Answer 23:
Molarity = \(\frac { No. of moles in the solute }{ Volume of solution in ml }\) x 1000
Moles of oxalic acid dihydrate in the solution = 0.1 x 0.25 = 0. 025 moles.
Molecular mass of oxalic acid dihydrate is 2+12 x 2 + 16 x 4 + 2(2+16) = 126
Mass of the acid used = 126 x 0.025= 3.15g

Answer 24:

Answer 25:

In diborane 4 terminal H-atom and the 2 boron atom lies one plane. Above and below this plane, there are 2 bridging H-atom. Each bridged H atom is bonded to 2 boron atom only by sharing of 2 electrons. Such a bond is called 3 centered 2 elec¬tron bond. Thus diborane have two (B-H-B) bonds, ie., two 3-centered 2 electron bond and four (B-H) bonds, ie., four 2 centered 2 electron bond.

Answer 26:
Larger the value of K, greater is the extent to which the reactants are converted into the products.

• If K >10³, the product predominates over reactants at equilibrium. If K is very large the reaction proceeds nearly to completion.
• If K<10³, the product predominates over product. If K is very small the reaction proceeds to very small extend or rarely.
• If K is in the range of 10^-3 to 10³, appreciable concentrations of both reactants and products are present.

Prediction of direction of a reaction

The reaction quotient in terms of concentration or concentration Quotient (Q) with molar concentrations (Q_c) and with partial pressures (Q_p) is related to the equilibrium constant (K) for the reaction.
For a general reaction, aA+ bB ⇌ cC + dD

• If Q_c > K_c, the reaction will proceed in the direction of reactants (reverse reaction)
• If Q_c < K_c, the reaction will proceed in the direction of the products (forward reaction)
• If Q_c = K, the reaction is at equilibrium.

Answer 27:
a. H²O² decomposes in the presence of light and alkali content in glass. To prevent decomposition H²O² is stored in wax – lined glass or plasic vessels indark.
b. Hard water do not form lather easily with soap, due to the presence of dissolved salts in it.

Answer 28:

Answer 29:

Answer 30:

Since the bond order is 3, there is a triple bond in N² and the bond energy is very high. Since all the electrons are paired. It is diamagnetic.

Oxygen has unpaired electrons and hence I it is paramagnetic in nature.

Answer 31:
Crystallization:
This is one of the most commonly used techniques for the purification of solid organic compounds. It is based on the difference in the solubilities of the compound , and the impurities in a suitable solvent.
e.g., sugar and salt.

Simple distilation :
It is the process of eva-poration followed by condensation. It is used for separating a liquid which does not decompose on boiling from other liquids = having diferent boiling points or should contain a non-volatile component,
e.g., Benzene and Toluene. The vapours of a substance formed are condensed and the liquid is collected in the conical flask.

Distillation under reduced pressure: The method is used to separate those liquids which decompose at or below their normal ; boiling points. In this method, the distillation is carried at a lower pressure of 10 – i 20 mm Hg, so that the liquid can be boiled i at lower temperature without undergoing decomposition, e.g., Glycerol can be sep- arated from spentlye in the soap industry.

Paper chromatography: Partition chromaography is based on continuous differential partitioning of components of a mixture between stationary and mobile phases, Paper chromatography is a type of partition chromatography. In paper chromatograph, a special quality paper known as chromatography paper is used. Chromatography paper contains water trapped in it, which acts as the stationary phase.

Answer 32:
1. The electron in an atom revolve around the nucleus only in certain circular path called orbits.
2. The energy of the electron in a particular orbit remains constant.
3. Only those orbits are permitted in which the angalar momentum of the electron is a whole number of multiple of h/27r, where h is plank’s constant.
4. Energy is emitted or absorbed by an atom only when an electron moves one from one orbit to another.

Merits

1.  It could account for the stability of hydrogen atom
2.  It could account for the line spectra of hydrogen atom and hydrogen like ions (for example, He⁺, Li²⁺, Be³⁺, and so on)

Demerits

1. Bohr’s theory was also unable to explain the splitting of spectral lines in the presence of a magnetic field (Zeeman effect) or an electric field (Stark effect).
2. It could not explain the ability of atoms to form molecules by chemical bonds

Answer 33:
a. Alkali metals dissolve in liquid ammonia giving deep blue solutions which are conducting in nature. The blue colour of the solution is due to ammoniated .electrons which absorb energy in the visible region of light.
b. Mg and Li shows diagonal relationships. Both have similar size and similar electronegativity.
c. Sodium carbonate acts as an alkali be-cause when dissolved in water, it dissociates into the weak acid, carbonic- acid and the strong alkali sodium hy droxide.
d. The hydration enthalpies of BeSO₄ and MgSO₄ are quite high because of the small size of Be²⁺ and Mg²⁺ ions. These hydration enthalpy values are higher than – their corresponding lattice enthalpies and therefore, BeSO₄ and MgSO₄ are highly soluble in water.

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Previous Year Question Paper 2017

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to Candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provied.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Question 1:
a. Determine the number of moles present in 0.55 mg of electrons.
imgg
i. 1 mole
ii. 2 moles
iii. 1.5 moles
iv. 0.5 mole [1]

b. Give the empirical formula of the following. [2]
C₆H₁₂O₆, C₆H₆. CH₃COOH, C₆H₆C₁₆

c. Two elements, carbon and hydrogen combine to form C₂H₆, C₂H₄ and C₂H₂. Identify the law illustrated here. [1]

Question 2:
a. i. Write the electronic configuration of chromium (Z=24).
ii. Find the number of electrons in the subshells with azimuthal quantam number l=2.
iii. Represent the orbital with quantum numbers n = 1 and 1 = 0.
b. Give the mathematical representation of Heisenberg’s uncertainty principle and its one important significance.

Question 3:
Electron gain enthalpy is one of the important periodic property.
a. Define electron gain enthalpy. [1]
b. Explain any two factors affecting electron gain enthalpy. [2]
c. Write the oxidation state and covalency of Al in (A/ F₆)^3- [1]

Question 4:
The geometry of the molecule is decided by type of hybridization.
a. Discuss the shape of PCl₅ molecule using hybridization. [2]
b. Give the reason for the high reactivity of PCl₅ [2]
c. Isoelectronic species have the samebond order. Among the following, choose the pair having same bond order. Among the following, choose the pair having same bond order.
CN^–, O₂^– ,NO⁺, CN⁺

Question 5:
a. Give the reason behind the following.

i. The glass window pannels of old buildings are thicker at the bottom than at the top. [1]
ii. Sharp glass edges are heated for making them smooth. [1]

b. Maxwell and Boltzmann have shown that actual distribution of molecular speeds depends, on temperature and molecular mass.
i. What do you mean by most probable velocity? [1]
ii. At the same temperature which will move faster, N₂ or Cl₂ ? [1]

Question 6:
a. Some macroscopic properties are given below. Help Reena to classify them into two groups under suitable titles.
[Heat capacity, Entropy, Refractive in¬dex, Surface tension.] [2]
b. For the reaction
2A_(g) + 2B_(g) → 2D_(g)
∆U°= -10.5 kJ/mol
∆S°= – 44.1J/k/mol at 298 K.
Calculate ∆G° for the reaction. [2]

Question 7:
a. Classify the following solutions into acidic, basic and neutral
NaCl, NH₄NO₃, NaCN, NaNO₂ [2]
b. pH of blood remains constant in spite of the variety of goods and spices we eat. Give a reason. [1]
c. The solubility ofMg(OH)₂ at 298K is 1.5 x 10^-4.Calculate the solubility product.[2]

Question 8:
Permanganate ion reacts with bromide ion in basic medium to give manganese dioxide and bromate ion. Write the balanced equa¬tion for the reaction using oxidation number method.
Skeletal equation is
MnO₄^– + Br^– → MnO₂ + BrO₃^– [3]

Question 9:
Hydrogen is the most abundant element in the universe, But in free state it is almost not found in earth’s atmosphere.
a. Suggest any three methods for the preparation of H₂ gas by selecting suitable substance given below.

b. Do you expect carbohydrides of the type C_nH_2n+2to act as Lewis acid or base? Why?

Question 10:
The s-block of periodic table constitutes alkali metals and alkaline earth metals.
a. The hydroxides and carbonates of sodium and pottassium are more soluble than that of corresponding salts of Magnesium and Calcium. Explain. [2]
b. Write the chemical name of the following:
i. Caustic soda
ii. Baking soda
iii. Slaked lime
iv. Milk of lime [2]

Question 11:
Borax is an important compound of Boron.
a. The solution of borax is alkaline. Give a reason. [2]
b. Give any two uses of borax. [1]
c. Diamond has covalent bonding. Yet it has high melting point. Give a reason. [1 ]

Question 12:
a. Give the structural formula of the following compounds:
i. 2, 4, 7 – Trimethyloctane
ii. 2 – chloro – 4 – methyl pentane [2]
b. CH₃C₂ or (CH₃)₂CH -which is more stable? Explain. [2]
c. Explain the chemistry behind crystallization. [2]
Or
a. Give the IUPAC names of the following:

b. Which is more stable (CH₃)₃ C⁺ or CH₃C⁺H₂? Give a reason. [2]
c. Give the chemistry behind distillation under reduced pressure. [2]

Question 13:
Benzene and benzenoid compounds show aromatic character.
a. Select the aromatic compounds from the following: [1]

b. Suggest a method to convert Ethyne to benzene. [2]
c. Give the products formed when benzene reacts with
i. CH₃ Cl/AlCl₃
ii. Cl₂ /hυ [2]

Question 14:
Environmental pollution is the effect of undesirable change in surroundings that have harmful effect on plants, animals and human beings.
a. Explain the adverse effect of global warming. [2]
b. Choose the one which is not a component of photochemical smog.
i. NO₂
ii. O₃
iii. SO₂

Answers

Answer 1:
1. a.i. 1 mole
Mass of one electron = 9.1 x 10^-28 g
= 9.1 x 10^-25 mg
Mass of 1 mol of electron
= 9.1 x 10^-25 x 6.022 x 10^-23= 0.55 mg
So 0.55 mg of electron = 1 mol of electron

b. Empirical formula of C₆ H₁₂O₆ is CH₂O
Empirical formula of C₆H₆ is CH
Empirical formula of CH₃COOH is CH₂O
Enpiric formula of C₆H₆Cl₆ is CHCl
c. Law of multiple proportion.

Answer 2:
a. i. ₂₄Cr – 1s² , 2s², 2p⁶, 3s², 3p⁶, 4s¹, 3d⁵ or [Ar] 4s¹, 3d⁵
ii. 10 electrons in d subshell.
iii. 1s

b. Heisenberg’s uncertainty states that it is impossible to determine simultaneously and precisely both the exact position and exact momentum or velocity of a subatomic particle like an electron.
Mathematically, ∆x ∆p ≥ \(\frac { h }{ 4\pi }\)

where ∆p is the uncertainty in the momentum of the particle, ∆x is the uncertainty in position.
From this equation, it is seen that if ∆p increases, the ∆x decreases, and vice versa. It is also can be written as follows:
∆x ∆p ≥ \(\frac { h }{ 4\pi m }\)

Answer 3:
a. Electron gain enthalpy is the enthalpy change when an electron is added to the outer most shell of an isolated gaseous atom in the ground state.
b. The factors affecting electron gain enthalpy are atomic size, nuclear charge, shielding effect, electronic configuration etc. As the atomic size increases. ∆_eg H decreases. When nuclear charge increases, electron gain enthalpy increases.
c. Oxidation state is +3
Covalency is 6.

Answer 4:
a. In PCl₅, five sp³d orbitals of phosphorus overlap with singly occupied p-orbitals of chlorine atoms to form five P-Cl bonds. Three P-Cl bond lie in one plane and make bond angle of 120°. These bonds are equitorial bonds. The remaining two P-Cl bond lye above and below the equitorial plane making an angle of 90° with the plane. These bonds are called axial bonds.

b. Two P-Cl axial bonds are slightly elongaed to minimise repulsion from equitorial bond pairs. So axial bonds are weaker than equitorial bonds in PCl₅.
c. CN^– and NO⁺

Answer 5:
a.i. Glass is a very viscous liquid. So it has a tendency to flow very slightly. Hence the window panes of old buildings are thicker at the bottom than at the top.
ii. On heating, the glass melts and the surface of the liquid tend to take the rounded shape at the edges, which makes the edges smooth.
b. i. Most probable velocity is the velocity possessed by a maximum number of gas molecules.
ii. N₂.

b. Given All0 = -10.5 kJ/mol = -10.5 x 103 J/mol
AS0 = -44.1 J/K/ mol, T= 298 K We know that AH° = AU° + AnRT Here AH° = -10500 + (-1)x 8.314 x 298 = -12978 J/ mol
AG° = AH0 – T AS0 = -12978 – (298 X44.1) = -164 J/ mol = -0.164 kJ/ mol.

Answer 6:
a.

Extensive properties	Intensive properties
Heat capacity	Refractive Index
Entropy	Surface tension

b. Given ∆U° = -10.5 kJ/mol = -10.5 x 10³ J/mol
∆S° = -44.1 JIKI mol, T = 298 K
We know that ∆H° = ∆U° + ∆nRT
Here ∆H° = -10500 + (-1)x 8.314 x 298
= -12978 J/ mol
∆G° = ∆H° – T∆S° = -12978- (298 X 44.1)
= -164 J/ mol = -0.164 kJ/ mol.

Answer 7:
a. Neutral – NaCl
Acidic – NH₄NO₃
Basic – NaCN, NaNO₂
b. Because blood is a buffer solution.
c. Mg (OH)₂ → Mg²⁺ + 2 OH^–
Solubility: S S 2S
K_sp = [Mg²⁺][OH^–]² = S X (2S)² = 4S³
= 4 x (1.5 x 10^-4 )³ = 1.35 x 10^-11

Answer 8:
Step 1 : The skeletal equation is :
MnO₄^– +Br^– → MnO₂ + BrO₃^–

Step 2 : Assign oxidation number each element and identify the elements under-going change in oxidation number.
Mn⁺¹O₄^-2 + Br^-1 → Mn⁺⁴O^-2₂ + BC⁺⁵O₃^-2
Here the oxidation number of Mn and Br are changed.

Step 3 : Calculate the increase and decrease in oxidation number and make them equal by multiplying with suitable number.
2MnO₄^– + Br^– → 2 MnO₂+ BrO₃^–

Step 4 : Since the reaction takes place in the basic medium, 20H^– ions on the RHS to balance the ionic charges on both sides.
2MnO₊₄^– + Br^– → 2 MnO₂ + BrO₃^– + 2OH^–

Step 5 : Now balance hydrogen atom by adding a sufficient number of H₂O molecules. Here add one H₂0 molecule on LHS.
2MnO₊₄^–+ Br^– +H₂O → 2MnO₂+ BrO₃^–+ 2OH^–
This is the balanced equation.

Answer 9:
a. i. 2Na + 2H₂O → 2 NaOH + H₂
or
2Na + 2 HCl → 2NaCl + H₂
ii. Zn + 2 HCl → ZnCl₂ + H₂
OR
Zn + 2 NaOH → Na₂ZnO₂ + H₂
iii. CaH₂ + 2H₂O → Ca(OH)₂ + 2H₂
iv. 2Al + 6 HCl → 2AlCl₃ + 3H₂ (Any three)

b. C_n H_2n+1 is neither a Lewis acid nor a Lewis base due to the absence of vacant orbitals or lone pairs of electrons on carbon.

Answer 10:
a. This is due to greater atomic radii (size) or lesser lattice enthalpy of sodium and potassium ions.
b. i. Caustic soda : Sodium hydroxide (NaOH)
ii. Baking soda : Sodium bicarbonate (NaHCO₃)
iii. Slaked lime : Calcium hydroxide (Ca(OH)₂)
iv. Milk of lime : Magnesium hydroxide (Mg(0H)₂)

Answer 11:
a. Borax dissolves in water to give NaOH and orthoboric acid. Since NaOH is a strong alkali and orthoboric acid is a weak acid, the solution is basic in nature.
Na₂B₄O₇ + 7 H₂O → 2NaOH + 4H₃BO₃

b. Borax is used for the detection of transition elements by Borax bead test. It is used for the manufacture of heat-resistant glasses, glass-wool, and fiberglass. It is also used as a flux for soldering metals, for heat, scratch and stain resistant, glazed coating to earthenwares and as a  constituent of medicinal soaps. :
c. Diamond has a three-dimensional network structure with extended covalent bonding.
Since it is very difficult to break these covalent bonds, it has high m.p Or, due to the tetrahedral (sp³) hybridization of carbon atoms in diamond.

Answer 12:
a. i.

b. CH₃^– – CH₂^– is more stable than (CH₃)₂CH^– since for carbanions the stability order 1° > 2° > 3° due to inductive effect.

c. Crystallization is based on the difference in the solubilities of the compound which is dissolved in a solvent in which it is sparingly soluble at room temperature but appreciably soluble at higher temperature. The solution is concentrated to get a nearly saturated solution at a higher temperature. On cooling the solution , pure compound crystallizes out and is removed by filtration.

OR

a. i. 3- Bromo-3-chloroheptane
ii. 4-Ethyl-2-methylaniline

b. (CH₃)₃C⁺ is more stable than CH₃ – CH₂⁺ since the stability of carbocations follow the order 3° > 2° > 1° due to inductive effect and hyperconjugation.

c. This method is used to purify liquids having very high boiling points and those, which decompose at or below their boiling points. Such liquids are made to boil at a temperature lower than their normal boiling points by reducing the pressure on their surface. The pressure is reduced with the
help of a water pump or vacuum pump.

Answer 13:
a. Aromatic compounds are :

b. Ethylene on passing through a red-hot iron tube at 873 K, we get benzene (C₆H₆).
c. i. Toluene (C₆H₅ – CH₃)

Answer 14:
a. Due to global warming, the average global temperature will increase. This will lead to the melting of polar ice caps and flooding of low lying areas all over the earth. Increase in global temperature results in infectious diseases like dengue, malaria, yellow fever, sleeping, sickness etc.
b. iii. SO₂

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Chemistry Previous Year Question Paper 2018

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to Candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provied.
• Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
Name the quantum number which gives the spacial orientation of an orbital with respect to standard as et of coordinate axes.

Question 2:
Among N^3-, O², F^–, Na⁺ and Al³⁺, which one has the smallest size?

Question 3:
Which pollutant in water causes brown mottling of teeth ?

Question 4:
Examine the following graph and name the gas law corresponding to it.

Question 5:
If Z – axis is the internuclear axis, name the type of covalent bond formed by the overlapping of two Py – orbitals.

Question 6:
Which among the following measurements, contains the highest number of significant figures?

Question 7:
Write the formula of the basic structural unit of silicates.

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
Write any two limitations of octet rule.

Question 9:
Draw the ‘sawhorse’ projections of the eclipsed and staggered conformations of ethane.

Question 10:
Give the relation between Kp and Kc for the reaction given below.

Question 11:
State and illustrate the law of multiple proportions.

Question 12:
a. Define ‘ normal boiling point’ of a liquid.
b. Give a reason for the use of pressure cooker to cook food, at high altitudes.

Question 13:
Write two important results observed during the photoelectric effect.

Question 14:
Differentiate state functions from path functions and give one example for each.

Question 15:
Define the terms, Biochemical Oxygen Demand (BOD) and Eutrophication.

Question 16:
Give the chemical equation for the conversion of hexane to benzene. Write the name of the process.

Question 17:
H₂0 and HSO₄, can act both as Bronsted acids and bases. For each case give he corresponding conjugate acid and conjugate base.

Question 18:
What is metamerism ? Write the metamers of C₄H₁₀O.

Question 19:
What are Zeolites ? Give any two uses of zeolites.

Question 20:
First law of thermodynamics can be stated as Δu = q + w. How can this equation be expressed for:
a. An isothermal reversible change ?
b. A process carried out at constant volume ?

Answer any seven from question numbers 21 to 29. Each carries three scores.

Question 21:
Predict the products :

Question 22:
Redox reactions are classified into four types. Describe any three of them with suitable examples.

Question 23:
Enthalpies of formation of some compounds are given below:

Using these data, calculate the enthalpy of reaction for N₂O_4(g) + 3CO_(g) → N₂ O_(g) + 3CO_2(g)

Question 24:
Sketch the structures of graphite and diamond. What is the impact of structure on physical properties of these allotropes?

Question 25:
Briefly explain the different types of hydrides.

Question 26:
Calculate the amount of CO₂(g) produced by the reaction of 32g of CH₄ and 32g of O₂.

Question 27:
Give reasons for the following :
a. ‘O’ has lower ionization enthalpy than N and F.
b. Cl has higher negative electron gain enthalpy than F.

Question 28:
Write the postulates of kinetic molecular theory of gases.

Question 29:
The ionization constant of nitrous acid is 4.5 i x 10^-4. Calculate the pH of 0.04M solution of j nitrous acid in water.

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
Name the commercial process used to prepare sodium carbonate and write the chemical equations of the steps involved in it.

Question 31:
What is ‘sodium fusion extract’? How the presence of N, S and halogens inorganic compounds are detected?

Question 32:
The diatomic species Ne₂ does not exist, but Ne₂ can exist. Explain on the basis of molecular orbital theory.

Question 33:
Explain how the different series of lines are formed in the hydrogen spectrum. Derive an equation to find the waW number of a line in the hydrogen spectrum.

Answers

Answer 1:
Magnetic quantum number

Answer 2:
Al³⁺

Answer 3:
Fluoride (P)

Answer 4:
Gay-Lussac’s law

Answer 5:
π bond

Answer 6:
a

Answer 7:
SiO₄^4-

Answer 8:
The incomplete octet of the central atom
In some compounds, the number of electrons surrounding the central atom is less than eight. This is especially the case with elements having less than four valence electrons.

Odd-electron molecules
In molecules with an odd number of electrons like nitric oxide, NO and nitrogen dioxide, N02, the octet rule is not satisfied for all the atoms

Answer 9:

Answer 10:
K_p = K_c (RT)^∆n
∆n = 3 – 2 = 1
K_p = K_c (RT)¹= K_c(RT)

Answer 11:
Law of Multiple Proportions
According to this law, if two elements can combine to form more than one compound the masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers

Here the masses of oxygen which com¬bine with a fixed mass of hydrogen bear a simple ratio, i.e., 16: 32 or 1: 2.

Answer 12:
a. The temperature at which a real gas obeys ideal gas law over an appreciable range of pressure is called Boyle temperature or Boyle point.
b. At high altitudes atmospheric pressure is low. Therefore liquids at high altitudes boil at lower temperatures in comparison to that at sea level. Since water boils at low temperature on hills, the pressure cooker is used for cooking food.

Answer 13:
i. There is no time lag between this striking of light beam and ejection of an electron from the metal surface.
ii. The no.of electron ejected is proportional to the intensity or brightness of light

Answer 14:
A state function is a property of the system whose values depends upon the initial and final states of the system and independent of the path by which the state is reached.
Path function is a property of the system whose values depend on the path followed,
eg. Heat (q), Work (w).

Answer 15:
BOD is Biochemical Oxygen Demand. It is defined as the amount of oxygen in milligrams dissolved in water needed to break down the organic matter present in one litre of water for five days at 20 °C.Pure water contains BOD of 0-3 ppm. 5 ppm means water is contaminated.
The process in which the nutrient enriched water bodies support a dense plant population, which kills animal life by depriving it of oxygen and results in subsequent loss of biodiversity is known as eutrophication

Answer 16:
Alkanes having six or more carbon atoms on heating to 773 K at 10^-20 atmospheric pressure in presence of Cr₂O₃ or V₂O₅ or MO₂O₃ catalyst give aromatic compounds. This process is known as aromatization.

Answer 17:
H₂O : Conjugate acid – H₃O⁺ Conjugate base – OH^–
HS0₄^– : Conjugate acid – HSO₄^–
Conjugate base – SO₄^2-

Answer 18:
Metamerism: It arises due to different alkyl chains on either side of the functional group in the molecule. For example, C₄H₁₀O represents methoxypropane (CH₃OC₃H₇) and ethoxyethane (C₂H₅OC₂H₅).

Answer 19:
Zeolites : If aluminum atoms replace few silicon atoms in three-dimensional network of silicon dioxide, overall structure known as aluminosilicate, acquires a negative charge. Cations such as Na⁺, K⁺ or Ca²⁺ balance the negative charge. Examples are feldspar and zeolites. Zeolites are idely used as a catalyst in petrochemical industries for cracking of hydrocarbons and isomerisation, e.g., ZSM- 5 (A type of zeolite) used to convert alcohols directly into gasoline. Hydrated zeolites are used as ion exchangers in softening of “hard” water.

Answer 20:
a. q = -w = 2.303 RT log \(\frac { { V }_{ f } }{ { V }_{ i } }\)
q = -w
b. ∆u = ∆w

Answer 21:
a. CH₃– CH₂– CH₂– Br 1 – bromopropane

Answer 22:
1. Combination reactions. The reaction involves combination of a compound from two or more components atleast one of which must be in the elemental form or both the components are in the elemental state.
eg., CO + O₂ \(\underrightarrow { \Delta }\) C0₂

2. Decomposition reactions. The reaction involves decomposition of a compound into two or more components atleast one of which must be in the elemental state.
eg., 2NaH \(\underrightarrow { \Delta }\) 2Na + H₂

3. Displacement reactions. In a displace-ment reaction, an ion or an atom in a com-pound is replaced by an ion or an atom of another element,
eg., A + BC → AB + C

a. Metal displacement reaction.
A metal in a compound can be displaced by another metal in the uncombined state.

b. Non-metal displacement reaction.
This include hydrogen displacement and a rarely occuring reaction involving oxygen displacement.

Answer 23:
Enthalpy of reaction
(∆_r H)= [81 +3(-393)] -[9.7 +3(-110)]
= [81 – 1179] – [9.7 – 330] = -778kJmol^-1

Answer 24:
Graphite. Graphite has layered structure. Distance between 2 layers is 340 pm. C-C bond length within the layer is 141.5 pm. Each carbon atom in hexagonal ring undergoes sp² hybridisation with 3 neigh-bouring carbon atoms. The 4^th electron present in the unhybridised p- orbital is used for forming a π bond.

Diamond: Purest form of carbon. In dia-mond, each carbon atom is in sp3 hybridised state and is tetrahedrally bonded to 4 other carbon atom. The C-C bond length is 154 pm and C-C-C bond angle is 109°28. This 3 dimensional net work structure makes diamond harder and a bad conducor of electricity.

Answer 25:
Binary compounds of hydrogen with other elements are called hydrides. It can be ex-pressed as EH_x(MgH₂) or E_mH_n (B₂H₆).

ionic or Saline Hydrides
There are stoichiometric compounds of H₂ formed with most of the s-block elements j which are highly electropositive in character. The ionic hydrides are crystalline, nonvolatile and non-conducting in solid state.
In molten state, ionic hydrides conduct I electricity. Salts like hydrides are strong bases such as LiH, BeH₂, MgH₂.

Covalent or Molecular Hydrides
Covalent hydrides are formed by most of the p-block elements. It have very low con¬ductivity and are acidic in nature. Covalent hydrides are soft and have very low melting and boiling points,
eg., CH₄, NH₃

Molecular hydrides are further classified j according to the relative numbers of electrons and bonds in their lewis structure,

a. Electron-deficient hydrides. These hydrides are deficient in electrons to write their conventional lewis structure.
eg: group 13 elements (B₂H₆).

b. Electron-precise hydrides. These hydrides have the required no: of electro¬ns to write their conventional lewis structure,
eg., group 14 elements (CH₄).

c. Electron-rich hydrides. These hydrides have excess which are present as lone pairs, eg. group 15-17 elements (NH₃ has 1 lone pair, H₂O has 2 lone pairs).

Metallic or Interstitial Hydrides (Non- stoichiometric)
These hydrides are formed by many d- block and f-block elements. Metallic hydrides are hard, possess metaliclusture, conduct electricity and show magnetic properties. eg., LaH_2.87, Y₆H_2.55. These hydrides are non-stoichiometric being deficient in hydrogen.

Answer 26:
To solve such questions you must write a balanced reaction first.
CH₄ (g)+2O₂ (g) → CO₂ (g) +2H₂O (g)
The molecular mass of methane is 16
32 grams of Methane mean 2 mole
32 grams of Oxygen mean 1 mole
2 moles of Oxygen for every mole of methane. So that makes oxygen the limiting reagent. So 1 moles of 02 will form 0.5 moles of C0₂.
0.5 mole of CO₂ = 0.5*44 = 22 grams
So 22 grams of CO₂will be produced

Answer 27:
a. Oxygen has outer electronic configuration 2s² 2p⁴ removal of one electron from the 2p subshell will make its configuration2s² 2p³ thus it attains a half-filled configuration thus lesser energy is required to remove an electron from oxygen where-as in nitrogen the electronic configuration 1s² 2s² 2p³ it has a stable half filled configuration and thus more energy is required to remove an electron salts.

from nitrogen, in case of flourine, the electronic configuration is 2s²2p⁵ it has to gain one more electron to attain noble gas configuration and become stable thus more energy is required to remove an I electron from flourine thus ionisation enthalpy of oxygen is lesser than nitrogen or fluorine.

b. Cl has more negative electron gain enthalpy than F. F has less negative electron gain enthalpy because in it the added electron goes to the smaller { energy level (n=2) and hence suffers ‘ significant repulsion from the electrons already present in this shell also flurine possesses high charge density.

Answer 28:
All gases are made up of a large number of extremely small particles called molecules.

• The molecules are separated from one another by large distances so that the actual volume of the molecules is negligible as compared to the total volume of gas.
•  The molecules are in a state of continuous rapid motion in all directions. During their motion, they keep on colliding with one another and also with the walls of the: container.
• Molecular collisions are perfectly elastic, there is no net loss or gain of energy in their collisions. However, there may be a redistribution of energy during such collisions,
• There are no attractive forces between the molecules. The move completely independent of each other.

Answer 29:
NO_-2 + H₂O ⇌ HNO₂ + OH^–
K_h= [ HNO₂ ] [ OH^– ] /NO^– ₂]
Kw / ka = 10^-14 / 4.5 x 10^-4 = 0.22 x 10^-10
Now, If x moles of the salt undergo hydrolysis,  then the concentration of various species present i in the solution will be:
[NO^-2] = 0.04 -x;0.04
[ HN0₂ ] = x [ OH-] = x
K_h = x² / 0.04 = 0.22 x 10^-10 x2
x² = 0.0088 x 10^-10
x = 0.093 x 10^-5
[ OH^– ] = 0.093 x 10^-5M
[H₃0⁺] = 10^-14] / 0.093 x 10^-5] = 10.75 x 10^-9] M
pH = -log( 10.75 x 10^-9] ) = 7.96

Answer 30:
Sodium carbonate is generally prepared by Solvay Process. In this process, advantage is taken of the low solubility of sodium hydrogencarbonate whereby it gets precipitated in the reaction of sodium chloride with ammonium hydrogencarbonate. The latter is prepared by passing C02 to a concentrated solution of sodium chloride saturated with ammonia, where ammonium carbonate followed by ammonium hydro-gencarbonate are formed. The equations for the complete process may be written as :

2NH₃ + H₂0 + C0₂ → (NH₄)₂CO₃
(NH₄)₂CO₃+ H₂O + CO₂ → 2NH₄HCO₃
NH₄HCO₃+ NaCl → NH₄Cl + NaHCO₃

Sodium hydrogencarbonate crystal sepa¬rates. These are heated to give sodium carbonate.

2NaHCO₃ →Na₂CO₃ + C0₂ + H₂0

In this process NH₃ is recovered when the solution containing NH₄CI is treated with Ca(OH)₂. Calcium chloride is obtained as a by product.

Answer 31:
Nitrogen, sulphur, halogens and phosphorus present in an organic compound are detected by “Lassaigne’s test”. The elements present in the compound are converted from covalent form into the ionic form by fusing the compound with sodium metal. Cyanide, sulphide and halide of sodium so formed on sodium fusion are extracted from the fused mass by boiling it with distilled water. This extract is known as sodium fusion extract.

By fusing organic compound with sodium metal, the elements present in the compound forms corresponding water soluble salts.

Detection of Nitrogen:
N exist as NaCN in sodium fusion extract.

CN^– + Fe²⁺ \(\underrightarrow { FeS{ O }_{ 4 } }\) [Fe(CN)₆]^4-

On heating with con.H² SO⁴ , Fe²⁺ oxidised to Fe³⁺ to give prussion blue in colour.

3[Fe(CN)₆]^4- + 4Fe³⁺ \(\underrightarrow { x{ H }_{ 2 }O }\) Fe₄[Fe (CN)₆]₃.xH₂O Prussian blue

Detection of Halogens:
Halogen exist as halides (max.) in fusion extract. When AgNO₃ and HNO₃ is added they form AgX.
X^– + Ag⁺ → AgX ; (X = Cl, Br, I)

AgCI – white ppt
Agl – yellow ppt
AgBr – pale yellow

Detection of Sulphur:
Sulfur as Na2S is fusion extract when sodium nitroprusside added gives violet color.
Na²S + Na²[Fe(CN)⁵NO)] → Na⁴[Fe(CN)⁵ NOS] (violet colour)

Answer 32:
Electronic configuration of Ne2 is

Answer 33:
When electric discharge is passed through hydrogen gas enclosed in a discharge tube under low pressure and the emit¬ted light is analysed by a spectroscope, the spectrum consists of a large number of lines which are grtouped into different series. These series appear in different regions of light and are named after their discoveries. The complete spectrum is known as hydrogen spectrum.
According to Bohr’s model for Hydrogen
atom, E_n = -R_H\((\frac { 1 }{ { n }^{ 2 } } )\)
and ∆E = E_f -E_i
where E_fis the energy associated with final state while E_i is the energy of the initial state.

Here n_f and n_i represent final and initial electron orbits.

The frequency (υ) for the absorption and emission of the photon can be calculated as follows:

Plus One Chemistry Previous Year Question Papers and Answers

Kerala Plus One Physics Model Question Paper 3

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures, and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Questions 15 carry 1 score each. Answer any I four questions.

Question 1.
The branch of Physics which deals with the study of phenomena related to light.

a. Optics
b. Thermodynamics
c. Mechanics
d. Electronics

Question 2.
State the theorem of perpendicular axes on a moment of inertia.

Question 3.
Select a true statement from the following.
a. The distance traveled by light in one year through vacuum or air is an astronomical unit.
b. The range of time in Physics varies from 10^-14 sec to 10^-25 sec.
c. Lightyear is the largest practical unit of length.
d. Chandra Shekhar Limit (C.S.L) is the largest practical unit of mass.

Question 4.
When two objects collide, after collision they could move together, the collision is ……………………
(elastic, completely elastic, inelastic, completely inelastic)

Question 5.
List any two conditions for a motion of a body to be simple harmonic.

Questions 6 to 11 carry 2 scores each. Answer any 5 questions.

Question 6.
The possibility of falling backward with the ladder is more when you are high up on the ladder than when you just begin to climb. Explain why.

Question 7.
The displacement of y (in cm) of an oscillating particle varies with time t (in a sec) according to the equation. y = 2 cos (0.5 πt + π/3) Find the amplitude and period of the particle

Question 8.
Draw the stress-strain graph of a loading wire. Mark the following points:

1. Elastic limit
2. Fracture point
3. Plastic region
4. Elastic region.

Question 9.
Calculate the work done in lifting a body of mass 10 kg to a height of 10 m above the ground. 10 kg

Question 10.
a. Which among the following possess the highest specific heat capacity?

1. Water
2. Silver
3. Copper
4. Steel

b. You are in a restaurant waiting for your friend and ordered coffee. It has arrived. Do you add sugar to your friend’s coffee and then wait for him or do you add sugar after he arrives? Explain with respect to the concept of cooling.

Question 11.
A collision between two particles need not be the physical contact of two particles as in the case of scattering of the particle by a nucleus.
a. What is the quantity that remains conserved in all types of collisions?
b. Suppose an electron and a proton are projected with equal kinetic energy, What will be the ratio of their linear momentums if the proton is 1830 times heavier than an electron?

Questions 12 to 17 carry 3 scores each. Answer any five questions.

Question 12.
Motion along a plane is called two-dimensional motion. A body moving in two dimensions is found to have an acceleration in one dimension.

a. Identify the motion.

b. A ball thrown by a player reaches another player in 2s. What is the maximum height attained by the ball above the point of projection? (Take g= 10ms^-2)

c. In the figure, the point P on a wheel of radius R is in contact with the ground. What is the displacement of the point, when the wheel rolls a half revolution?

Question 13.
All physical quantities can be expressed in terms of dimension.
a. Write the physical quantities of the following dimensions:
i. [M¹L¹T¹ ]
ii. [M²L ²T²]
b. Check whether the equation T = \(T=2\pi \sqrt { \frac { m }{ g } }\) is dimensionally correct
T → Time period of a simple pendulum
m → mass of the bob
g → acceleration due to gravity

Question 14.
Kinetic theory of gases is based on the molecular picture of matter.
a. Write any two postulates of kinetic theory of gases.
b. Write short notes on:

1. Equipartition of energy
2. Mean free path

Question 15.
The stress-strain graph for wires of two materials A and B are given below.

a. Which material is more ductile?
b. When spring balances are continuously used for a long time, they show a wrong reading. Explain why?

Question 16.
Force is required to lift a body from the ground to a height h and work is measured as the product of force and magnitude of displacement.
a. Name the energy possessed by the body at maximum height. Write an equation for it.
b. A man of mass 60 kg carries a stone of mass 20 kg to the top of a multi-story building of height 50m. Calculate the total energy spent by him? (g = 9.8 m/s²)

Question 17.
The acceleration due to gravity o,n the surface of the moon is 1.7 m/s². what is the time period of a simple pendulum on the moon, if its time period on Me earth is 3.5 second?

Questions 18 to 22 carry 4 scores each. Answer any 4 questions.

Question 18.
A stone is thrown with the help of a sling with initial velocity V_Q at an angle θ from the horizontal.

a. Working of a sling is based on a law of vector addition.
b. With the help of a vector diagram, state this law.
c. Derive the expression for the maximum height reached by the

Question 19.
The velocity of sound depends on density (p) and modulus of elasticity (E). (The dimensional formula of E is ML^-1 T^-2)
a. State the principle of homogeneity.
b. Using the above principle, arrive at an expression for the velocity of sound. (Take K = 1).

Question 20.
Hooke’s law states that stress a strain.
a. What is the necessary condition for the above law to be valid?
b. Explain with the help of a graph, the relation between stress and strain for a given solid material under increasing tensile stress.

Question 21.
a. The figure shows the position-time graph of a body moving along a straight line.

1. Draw the velocity-time graph of the body.
2. From the graph, find the displacement in 20 seconds.

b. From the velocity-time graph of a body moving with uniform acceleration, deduce the velocity-time relation and the velocity displacement relation.

Question 22.
The motion represented by the equation, y(t) = A cos (ωt + Φ) is called simple harmonic motion (SHM).
a. Which one of the following examples ‘ closely represents SHM? Substantiate your answer.

1. The rotation of the earth about its axis.
2. Oscillations of a swing.

b. A vibrating simple pendulum of period T is placed in a lift which is accelerating downwards. What is the effect of this on the time period of the pendulum?

Questions from 23 to 26 carry 4 scores. Answer any 3 questions.

Question 23.
According to Newton’s law of motion, the force depends on the rate of change of momentum.
a. Name the law that helps to measure force.
b. Using the above law, deduce an expression for a force.
c. A man jumping out of a moving bus falls with his head forward. What should he do in order to land safely?

Question 24.
The flow of an ideal fluid in a pipe of a varying cross-section is shown.

a. Differentiate between streamline flow and turbulent flow.
b. State and prove Bernoulli’s principle.

Question 25.
The figure given below depicts the schematic representation of an engine.

a. Which type of engine is this, a heat engine or a refrigerator?
b. Write the 4 steps of operation in the Carnot cycle.
c. A Carnot engine is working with a temperature of 27°C and 327°C. Find its efficiency (η).

Question 26.
In a hammer throw event, a solid sphere of mass 16 kg is tied to a light 50 cm long chain. A sportsman gives it a constant moment of 30 Nm for 10 seconds and then throws the sphere. Consider the sphere as a point mass.
a. Find the moment of inertia about the axis of rotation.
b. If ‘L’is the angular momentum and τ is the torque. Show that τ = \(\frac { dL }{ dt }\)
c. Write an example for the motion in which an angular momentum remains constant.

Answers

Answer 1.
Optics

Answer 2.
This theorem is good for flat bodies which means, thickness much less than length and breadth. The theorem states that “the moment of inertia of a plana body about an axis perpendicular to its plane is equal to the sum of moments of inertia about two mutually perpendicular axes passing through the same point, lying on the plane”.

Answer 3.
d

Answer 4.
Completely inelastic.

Answer 5.
1. acceleration is directly proportional to displacement. i.e., a α y
2. Periodic motion.

Answer 6.

As the distance from the axis of rotation (r) increases, the torque also increases. When we are high on the ladder the, r is greater and so a small force in the perpendicular direction can cause a large torque. So there is a greater chance of falling.

Answer 7.
A pendulum whose period is 2 seconds is called seconds pendulum. y = A cos (ωt + ∅)

1. x = 20 cos (62.Bt + π/14) Amplitude = 20 icm
2. Frequency a> = 62.8
3. Initial phase = 14 Strain

Answer 8.

Answer 9.
Work was done = Force × displacement
W = mg × h = 10 × 9.8 × 10 = 980 J

Answer 10.
a. Water.
b. Add sugar as soon as the coffee arrives and then wait. This is Newton’s law of cooling. Thus when sugar is added to coffee, the temperature of coffee decreases. Hence the rate of cooling also decreases.

Answer 11.
a. Momentum is conserved
b. The kinetic energy of an electron

Answer 12.
a. Projectile motion

Answer 13.
a.

1. Momentum or impulse
2. Work, energy, torque

So the equation is wrong

Answer 14.
a. AverageThe average energy of a molecule of an ideal gas is proportional to the absolute temperature. PV = nRT at all pressure and temperature.
b.

1. According to equipartition theorem, total energy of a system is equally distributed among various degree of freedom.
2. Mean free. a path is the mean distance traveled by the molecules between two successive collisions.

Answer 15.
a. Material A is more ductile.
b.This is due to a phenomenon known as fatique. Due to continuous use for a long time, the elasticity of materials decreases. So they show a wrong reading.

Answer 16.
a. Potential energy U = mgh
b. m = 60 + 20 = 80 kg;
h = 50m; g= 9.8 m/s²
U= mgh = 80 × 9.8 × 50
= 39200J

Answer 17.
g_m = 1.7 m/s², T_m = ? T= 3.5 s

Answer 18.
a. Parallelogram law of vector addition.
b. It states that “if two vectors are represented both in magnitude and direction by the adjacent sides of a parallelogram drawn from a point, then the resultant vector is represented both in magnitude and direction by the diagonal of the parallelogram passing through the same point”.
c. Horizontal range (R). It is the horizontal distance covered by a projectile from the point of projection on the ground to the point on the ground where the projectile returns again. R = horizontal velocity x time of flight (The horizontal velocity v cosQ of the projectile will be a constant)

The above equation shows that R is maximum when sin 20 is maximum, ie., when 0 = 45°
The maximum horizontal range Rmax = \({ R }_{ max }=\frac { { u }^{ 2 } }{ g }\)

Answer 19.
a. Acca ordering to a principle of homogeneity, the dimensions of the same fundamental quantity must be the same on both sides of the equation.

Answer 20.
a. Hooke’s law states that within elastic limit stress is directly proportional to strain.

Consider a uniform wire suspended freely from a fixed point. The face end is subjected to a stress and strain is noted. In the above graph, stress is on Y-axis, and strain on X-axis.

In the initial stages as stress increases strain also increases linearly from 0 to A. Till A stress a brain. For the all-region AB the proportionality is lost but even in this region, the wire will partially recover its initial state.

Beyond B (B is called the elastic limit). The strain increases very rapidly and it is seen that the wire retains the law dimension’s on the removal of the force. Now its behavior is plastic.

Beyond this point, even without increasing the stress any further the wire extends and ultimately at D, it breaks. This point D is called Breakpoint or yield point.

Answer 21.
a. A slope of a displacement-time graph (x-t) gives velocity. Velocity in the interval 0 – 5 sec.

When we draw a velocity-time graph, we get a graph as shown in the figure

ii. An area under the velocity-time graph gives displacement. Area A = 2 × 5 + 2 × 5 = 0 displacement = 0
b. Consider a body moving with uniform acceleration ‘a’. Let u be the initial velocity at a time t = 0 and v be the final velocity at time t.

But from equation (1), we get t = \(\frac { v-u }{ a }\)

Answer 22.
a. A simple harmonic motion is special type of motion which is periodic and takes place continuously at regular intervals of time in which a body moves to and fro on a straight line about a fixed point under a restoring force which is directed always towards the fixed point and directly proportional to displacement at that instant from the fixed point.

An ideal simple pendulum is made of a heavy point mass body suspended from rigid support by an inextensible, weightless and perfectly flexible string. The body is free to oscillate in a vertical plane. When an undisturbed pendulum is in the position ‘SO’. ‘S’ is the point of suspension and ‘O’ is the center of gravity of the bob.

The position SO is the equilibrium position. If the bob is slightly pulled aside and released, the pendulum oscillates between Q and P. Q & P represents the position of a center of gravity of the bob in the displaced position during the oscillation, then the force at P is shown in the figure.

1. Weight, mg of the bob acting vertically downwards.
2. The tension along the string T.

Resolving mg we get mg sinθ and mg cosθ as shown in the figure. Here mg cosθ balances the tension and mg sinθ acts tangentially at P hence it acts as the restoring force.
Let SO = SQ = SP = L
Let OP = x
Restoring force F = mg sin θ (Restoring force tends to reduce angular displacement θ hence the ve sign).
If the displacement ‘x’ is small compared to 1 θ is small hence sinθ = θ Restoring force F = – mg θ

Answer 23.
a. Newton’s 2^nd law of motion.
b. The law state that the rate of change of linear momentum is directly proportional to the applied force and it takes place in the direction of applied force. According to the second law,


c. A man jumping out of a moving bus falls with his head forward because his body gets a forward momentum and has a tendency to continue in the state of motion (inertia of motion) so in order to land safely he should not stand stationary but continue in the state of motion by running for a while.

Answer 24.
a. Streamline flow is defined as a flow in which all the liquid particles that pass any given point follow the same path at the same speed.

When the velocity of flow exceeds the critical velocity, the flow becomes Turbulent. The flow of a liquid is said to be turbulent flow if the speed and direction of the liquid particles passing any point change with time.

b. According to Bernoulli’s theorem, the steady flow of an ideal liquid, the total energy per unit volume remains constant throughout the flow. France by Bernoulli’s theorem, kinetic energy + potential energy + pressure energy = a constant throughout the flow

Consider the steady flow of a liquid through a nonuniform tube as shown in the figure. The pressure area of cross-section and speed at A are P₁, a₁, v₁ and P₂, a₂, v₂, at B. A and B are at height h₁ and h₂ from the horizontal. Let in time at liquid near

Total energy at A = Total energy at B Thus Bernoulli’s Theorem is proved.

Answer 25.
Heat engine.

Adiabatic expansion → BC
Isothermal compression → CD
Adiabatic compression → DA
c. The efficiency of a Carnot engine working between two temperature T₁ and T₂ of hot and cold reservoir is given by

Answer 26.

c. A motion of the earth around the sun.

Plus One Physics Previous Year Question Papers and Answers

Kerala Plus One Physics Model Question Paper 2

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures, and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Questions 1 – 5 carry 1 score each. Answer any four questions.

Question 1.
What is the range of weak nuclear force?

Question 2.
During isothermal expansion the internal energy of gas became ………………

Question 3.
The main mode of transmission of heat by which the sun heats the surface of the earth is ……………

1. Conduction
2. Convection
3. Radiation
4. None of these

Question 4.
A constant force of 200 N displaces a body through 5 m in the direction of the force. Find the work done on the body.

Question 5.
Say true/false: “ All the false conductors are electrical conductors also”.

Questions 6 to 11 carry 2 scores each. Answer any 5 questions.

Question 6.
A physical quantity is given by A = \(h=\frac { { Fv }^{ 2 } }{ L }\). F is the force, v is the velocity and L is the angular momentum. Find the dimensions of h.

Question 7.
Position time graph of a body is given.

a. Estimate the velocity during the time interval t = 2s to t = 3s.
b. Displacement of an object is proportional to t³. Show that its acceleration is increasing with time.

Question 8.
One mole of an ideal gas expands from volume V₁ to Volume V₂ at a constant temperature T. Derive an expression for the work done.

Question 9.
The stress-strain graphs for two materials A and B are shown below (the graphs are drawn using the same scale) Which of the two is the stronger material?

Question 10.
A brass tumbler feels much colder than a wooden tray on a chilly day. Why?

Question 11.
Three vessels of different shapes are filled with water to the same height ‘h’ and their bottom parts are connected to manometers measuring the pressure. The water levels in ail the vessels remain the same.

a. Identify the above phenomenon.
b. Predict the pressure level shown by the manometers.

Questions 1217 carry 3 scores each. Answer any five questions.

Question 12.
a. The error in the measurement of the radius of a circle is 0.6%. Find the percentage error in the calculation of the area of the circle.
b. What is the number of significant figures in 0.00820 J?

Question 13.
A simple pendulum is an object suspended by a weightless and inextensible string fixed rigidly to support.

1. Under what conditions for the amplitude, are the oscillations of the pendulum simple harmonic?
2. The period of oscillation of the pendulum is T. What will be the period if the pendulum is suspended in a lift moving down with an acceleration equal to g/3.2

Question 14.
a. Will the passenger experience a decrease or an increase in his weight? Explain.2
b. What will be the effect if the cable is cut and the lift falls freely?

Question 15.
Elasticity is the property of matter that is characterized by atomic packing. For an elastic solid, stress applied is directly proportional to the strain produced in it. The stress versus strain graph for three materials A, B and C is shown below.

a. Which is more elastic A, B or C? Justify your answer.
b. If the bulk modulus of water is 2 × 10⁸ Nnr^-2. Find its compressibility.

Question 16.
When a mass is suspended on a metallic wire, the length of the wire increases slightly.
a. Name and state the law that relates to the restoring force developed in the wire and its deformation.
b. Draw the stress-strain graph of a loading wire. Mark the following points:

1. Elastic limit
2. Fracture point
3. Plastic region
4. Elastic region.

Question 17.
Gases have two specific heat capacities, C and Cv. Why?
b. Laplace pointed out that when sound is propagating through a gaseous medium, the change is adiabatic. Show that adiabatic bulk modulus is yΔp.

Questions 18 to 22 carry 4 scores each. Answer any 4 questions.

Question 18.
A rigid body is a body with a perfectly unchanging shape under the influence of an external force.


a. What do you mean by the center of mass of a rigid body?
b. A rigid beam of length L, breadth band depth d is supported near its ends as shown in the figure. A load W is suspended at its center of mass. Write the expression for the amount of sagging.
c. A steel beam of length 5 m is kept at a temperature of 20°C. On a hot day, the temperature rises to 40°C. What is the change in its length due to thermal expansion? (Coefficient of linear expansion of steel is 1.2 × 10^-5/°C).

Question 19.
Our earth has several artificial satellites. But the moon is the only natural satellite.
a. If acceleration due to gravity at the surface of the earth is ‘g’, arrive at the expression for acceleration due to gravity at a depth’.
b. Distance to the moon from the earth is 3.84 × 10⁸ m and the time period of the moon’s revolution is 27,3 days. Obtain the mass of the earth. (g = 6.67 × 10^-11 Nm²/kg²)

Question 20.
The rotational analog of force is a moment of force, also called torque.
a. The turning effect of the force is maximum when the angle between? and p is …………..
b. A wheel starting from rest acquires an angular velocity of 10 rad/s in two seconds. The moment of inertia of the wheel is 0.4 kg m². Calculate the torque acting on it.

Question 21.
When a horse suddenly starts moving, the rider falls backward.
a. Name and state the law used to explain the above theorem.
b. State the law of conservation of linear momentum and prove it on the basis of the second law of motion.

Question 22.
Viscosity is the frictional force in fluids.
a. When a small metal ball is falling through a viscous medium, what are the various forces acting on it? Using this arrive at an expression for terminal velocity.
b. Raindrops falling under gravity do not acquire very high velocity. Why?

Questions from 2326 carry 4 scores. Answer any 3 questions.

Question 23.
a. A heat engine is a device used to convert energy into energy.
b. Name the four processes taking place in the Carnot cycle. Draw indicator diagram of the Carnot cycle.
c. A hole is drilled in a copper sheet. The diameter of the hole is 4.24 cm at 27°C. What is the change in diameter of the hole when the sheet is heated to 227° C? (Coefficient of linear expansion of copper = 1.7 x 10^-5/°C)
d. Write four postulates of kinetic theory of gases.

Question 24.
The antiseptics used for cuts and wounds in human flesh have low surface tension. Due to low surface tension, they spread over the wounds easily.

a. In the following figure, the angle of contact 0 is
b. Surface tension causes capillarity. Define capillarity and arrive at the expression for a capillary rise in terms of surface tension.
c. In a capillary tube, water rises to a height. If the capillary tube is inclined at an angle 60° with the vertical, what will be the length of the water column in the tube?

Question 25.
Moment of inertia is the analog of mass in rotational motion. But unlike mass, it is not a fixed quantity.
a. Moment of inertia can be regarded as a measure of rotational inertia. Why?
b. Write any two factors on which the moment of inertia of a rigid body depends.
c. The moments of inertia of two rotating bodies A and B are lAand lB, (lA > lB) and their angular momentum is equal. Which one has greater kinetic energy? Explain.

Question 26.
The outer side of a circular track of radius 200 m is raised to make an angle of 15°
a. Which force provides the necessary cen tripetal force for a car taking the circular track?
b. Name the process by which the outer side of a curved track is raised a little above the inner side.
c. Using the data provided in this case, determine the maximum permissible speed to avoid skidding. (Given ps = 0.25)

Answers

Answer 1.
The range of a nuclear force is of the order of 10^-16m.

Answer 2.
Zero

Answer 3.
Radiation.

Answer 4.
Force = 200 N displacement = 5m
Work done = Force × displacement = 200 × 5 = 1000 J

Answer 5.
False

Answer 6.

Answer 7.


i.e., a α t, Hence acceleration increases with time.

Answer 8.
PV = nRT; here n = 1
We have a small amount of work done when volume changes through tv at pressure p. Let volume change from V₁ to V₂ isothermally,

Answer 9.
Material A is stronger than material B because it can withstand more load without breaking for material A, the break-even point (D) is higher.

Answer 10.
The thermal conductivity of brass tumbler is larger than a wooden tray. Hence a brass tumbler feels much colder than a wooden tray.

Answer 11.
a.Hydrostatic paradox.
b. Pressure at the same height is the same.

Answer 12.

b. 3

Answer 13.
1. Amplitude should be small.
2. The period of simple pendulum \(T=2\pi \sqrt { \frac { 1 }{ g } }\)
When a lift is moving down with an acceleration g/3.

Answer 14.
a. The passenger experiences a decrease in weight.

b. The passenger experiences weightlessness W’ = m (g – g) = 0

Answer 15.
a. Material A is more elastic. Because the strain of material A is smaller than that other and slope of A is more. Soan extension of A will be less than B and C. When they are subjected to same reforming force F.

Answer 16.
a. Hooke’s law. Hooke’s law states that when elastic limit stress is directly proportional to strain.

Answer 17.
a. Heat can be given to gas in two ways.
1. By keeping the pressure constant.
2. By keeping volume constant. In (1) gas expands, additional heat is needed to work.

Answer 18.
a. Centre of a mass of a rigid body in the point where the whole mass of the body is assumed to be concentrated.

Answer 19.

Answer 20.

Answer 21.
a. Newton’s 1st Law of motion. The law states that “ everybody continues in its state of rest or of uniform motion in a straight line unless compelled by some external unbalanced force to change that state”,
b. The law states that “ If no external force acts on a system of several particles, the total linear momentum of the system remains constant”.

Answer 22.
a. The constant speed of the object falling through a viscous medium is called terminal velocity. The vicious force, F = 6xr|rv Considering the motion of the body, viscous force = apparent weight of the object in the fluid. where 5 is the density of the material of the solid and a that of the fluid.

b.Rain drop falling under gravity is acted upon by weight, upthrust and viscous force. Hence it attains constant velocity.

Answer 23.
a. Heat energy into mechanical energy.
b. Isothermal expansion AB Adiabatic expansion BC Isothermal compression CD Adiabatic compression DA

d.
1. Gas molecules randomly move all the time and collide with each other and with walls of a container.
2. Size of molecules is negligible compared to the average distance between molecules.
3. Molecules are rigid spheres with no attraction or repulsion between themselves or container and so, all the internal energy is kinetic.
4. A collision between molecules and wall are elastic. In between collisions they move in straight lines with uniform velocity. Time of collision is very small compared to time available for free motion.

Answer 24.
a. Obtuse or θ > 90°

The capillary action is a result of both adhesion and surface tension. If a capillary tube is held vertical in a liquid which has a concave meniscus. There always exists an excess pressure equal to 2s/R on the concave side of liquid are interphase. Where ‘S’ is the surface tension and R is the radius of curvature of a meniscus. Pressure just below the meniscus is p 2s/R, where P is the atmospheric pressure. The pressure outside the tube at a level of the meniscus is the atmospheric pressure’P’. Since the pressure at points in the same level of liquid must be the same, the liquid is pushed up in the tube to the height ‘h’ as shown in fig(a). In this position, the pressure of liquids column of height ‘h’ becomes equal to 2s/R. ∴ \(hpg=\frac { 2s }{ R }\) where p is the density and ‘g’ is an acceleration due to gravity.
From fig (b)


l = 2h or length increases.

Answer 25.
a. Just as inertia resists translatory motion, when a rigid body rotates about an axis, there is a tendency to resist changes in uniform rotational motion. Moment of inertia resists change in rotational motion of the body.
b. Moment of inertia of a rigid body depends on the mass of particles and the distribution of particles about the axis of rotation, size, and shape.

Answer 26.
a. It is provided by the force of friction between the tires of the car and the road.
b. Banking of roads.

Plus One Physics Previous Year Question Papers and Answers

Kerala Plus One Physics Model Question Paper 1

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures, and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Answer any four questions from question numbers 1 to 5. Each carries one score.

Question 1.
State TRUE or FALSE, “weak nuclear force is the weakest fundamental force.

Question 2.
Two vectors \(\bar { A }\) and \(\bar { B }\) are such that \(\left| \bar { A } \times \bar { B } \right| =\bar { A } ,\bar { B }\) Then the angle between the two vectors is ……………

a. 45°
b. 90°
c. 60°
d. 180°

Question 3.
A satellite is revolving around the earth with a kinetic energy E. The minimum addition of kinetic energy needed to make its escape from its orbit is ………………………

Question 4.
A particle executing SHM is an example of

1. acceleration of constant magnitude and direction.
2. acceleration of changing magnitude and direction.
3. acceleration of changing magnitude but constant direction.
4. acceleration of constant magnitude but changing direction.

Question 5.
The young’s modulus Young’smaterial of a wire is equal to the

a. The stress required to increase its length four times
b. The stress required to produce unit strain
c. The strain produced in it
d. half the strain produced in it

Answer any four questions from question numbers 6 to 10. Each carries two scores.

Question 6.
When brakes are applied on a moving vehicle, it stops after traveling a distance. This distance is called stopping distance.
a. Write an expression of stopping distance in terms of initial velocity (u) and retardation (a).
b. If the initial speed is doubled keeping the retardation same, by how much will the stopping distance change?

Question 7.
A parallelogram law helps to find the mag
nitude and direction of the resultant of two forces.
a. State the law.
b. If the magnitude of the two vectors and their results are the same, what is the angle between the two vectors?
Parallelogram

result-

Question 8.
Select the CORRECT alternative.
a. When a force is applied to a moving body, its motion is retarded. Then the work is done; is

1. positive
2. negative
3. zero

b. In the stable equilibrium position, a body has

1. maximum potential energy
2. minimum potential energy

c. The rate of the kinetic energy versus position vector gives the rate of change of

1. momentum
2. velocity
3. force

d. According to a work-energy theorem, the work done by the net force on a particle is equal to the change in its

1. kinetic energy
2. potential energy

Question 9.
The wire has an unstretched length of 2.40 m and an area of a cross-section of 3.90 × 10^-7 m². Determine Young’s modulus Y of the material.

Question 10.
According to the kinetic theory of gases, gas molecules are always in random motion.
a. State the law of equipartition of energy.
b. What do you mean by ‘mean free path’? Give an equation for the mean free path.

Answer any four questions from question numbers 11 to 15. Each carries three scores.

Question 11.
Acceleration time graph of a body starts from rest as shown below:

a. What is the use of the accelerationtime graph?
b. Draw the velocity time graph using the above graph?
c. Find the displacement in the given interval of time from 0 to 3 seconds.

Question 12.
Ramesh observes the motion of an insect in a circle. He finds that it travels 6 revolutions in an anticlockwise direction for a time of 31.4 sec.
a. Find the angular velocity of the insect?
b. If the insect travels 4 revolutions in the clockwise direction for a time of 8.6 sec. What will be the angular speed averaged over the total time?

Question 13.
A circular racetrack of radius 300 m is banked at an angle of 150. The coefficient of friction between the wheels of a race car and the road is 0.2. Find :

1. The optimum speed of the race car to avoid wear and tear on its tires.
2. Maximum permissible speed to avoid slipping.

Question 14.
Rotational inertia is the tendency of a rotating body to resist any change in its state of rotational motion.

a. What do you mean by the radius of gyration of a rolling body?

b. The figure shows two different spinning poses of a ballet dancer.

In which spinning pose does the ballet dancer have less angular velocity? Justify! your answer.

Question 15.
A and B are two objects moving with velocities V_A and V_B?
a. What is the velocity of A relative to B?
b. Rain is falling vertically with a speed of
35 m/s. A woman rides a bicycle with a speed of 12 m/s in the east to west direction. What is the direction in which she should hold her umbrella?

Answer any four questions from question numbers 16 to 20. Each carries four scores.

Question 16.
a. The value of acceleration due to gravity is maximum at the

1. Poles
2. Equator ;
3. Centre of the earth

b. Find the height at which ‘g’ is reduced to g/2. 2 I

c. A rat and a horse are to be projected from earth into space. State whether the veloc ity is the same or different in projecting; each animal. Justify.

Question 17.
A person in an artificial satellite of the earth experiences weightlessness. The moon is a natural satellite of the earth.
a. Can a person on the moon experience weight? Why?
b. A satellite is revolving very close to the earth. What is the percentage increase in velocity needed to make it escape from the gravitational field of the earth?
c. Acceleration due to gravity ‘g’ depends on the distance ‘r’ from the center of the earth. Draw a graph showing the variation of‘g’with r’.

Question 18.
a. A solid sphere falling through a viscous
medium attains a constant velocity called terminal velocity after some time of its fall. What are the different forces acting, on the sphere? Derive an epression for terminal velocity in terms of the coefficient of viscosity of the medium. 3 b. Water kept in earthern pots gets cooled. Why?

Question 19.
Mechanical power is represented by P = FV +
Av3p; where F is the force, v is the velocity; A ! is the area and p is the density.
a. The dimensional formula of power is
b. Check the dimensional validity of the above , equation.
c. Which of the following equations can’t be obtained by the dimensional method?

Question 20.
While conducting a resonance column experiment in the laboratory, you can hear the maximum sound at a certain height.
a. Explain the phenomenon of sound.
b. Show that in a closed pipe at one end, the frequencies of the first three harmonics; are in the ratio of vt: v2: v3 = 1: 3: 5. 2!
c. Open pipes are preferred to closed ones in musical instruments. Why?

Answer any four questions from question numbers 21 to 25. Each carries 5 scores.

Question 21.
Raising the outer edge of a curved road a little above the inner edge is called banking of curves.
a. Derive an expression for the safe speed with which a car can negotiate a banked road by taking into account the friction between the tires and the road.
b. A machine gun fires bullets of mass 40g each with a speed 1200 ms1. The person can hold the gun with a maximum force of 144 N. What is the maximum number of bullets that can be fired per second from the gun?

Question 22.
Earth satellites are objects which revolve around the earth. Consider a satellite at a ‘ height ‘h’ from the surface of the earth.
a. Give an equation for its orbital velocity.
b. Obtain an equation for the period of the above satellite.
c. Distinguish between geostationary satellites and polar satellites.

Question 23.
The pressure of the atmosphere at any point is the weight of the air column of a unit cross-sectional area. Its unit is a bar.

a. Identify the diagram and write its use.
b. State Pascal’s law for transmission of fluid pressure and explain the principles j of working of a hydraulic lift.
c. The above arrangement is placed in an ; elevator which is accelerating upwards, i What happens to the possible height of ; the liquid column in the tube? Justify.

Question 24.
Aheatengineisadevicewhichconvertsheatenergy into work.
a. What is the working substance in an ideal heat engine?
b. Draw the Carnot cycle and explain its working.
c. Calculate the efficiency of an engine working between steam point and ice point.

Question 25.
a. Wave motion is the propagation of energy through a material medium due to repeated periodic motion.

1. Transverse waves cannot be propagated through gases. Why?
2. What was the condition assumed by Laplace in correcting Newton’s equation for the velocity of sound in a gas? Write the newton Laplace equation.

b. A source of the sound of frequency 256 Hz is in between a listener and a wall. If the source is moving towards the wall with a velocity of 5ms1, how many beats per second will be heard if the sound travels with a speed of 330ms’1?

Answers

Answer 1.
False. Gravitational force is the weakest fundamental force.

Answer 2.
45°

Answer 3.
E

Answer 4.
2

Answer 5.
The stress required to produce unit strain

Answer 6.
a. When vehicle comes to rest v = 0, a = a
substituting these values in

b. When a body comes to rest, work is done = change in kinetic energy

The stopping distance becomes 4 times the original distance.

Answer 7.
a. Parallelogram states that if two vectors
are represented both in magnitude and direction by the adjacent sides of a parallelogram drawn from a point, then the resultant vector is represented both in magnitude and direction by the diagonal of the parallelogram passing through the same point.
b. R = A + B + 2AB cosθ

Answer 8.
a. negative
b. minimum potential energy
c. momentum
d. kinetic energy

Answer 9.

[slope from graph may vary slightly and mark may be granted to possible correct answers irrespective of variations.]

Answer 10.
Law of equipartition energy:
It states that in any dynamical system in thermal equilibrium, the energy is equally distributed amongst its various degrees of freedom and the energy associated with each degree of freedom per molecule is 1/2k_BT, where k_B is Boltzmann’s constant and T is the absolute temperature of the system.

b. The average distance traveled by the molecules between two successive collisions is called the mean free path. Mean free path \(=\frac { l }{ \sqrt { 2n\pi { d }^{ 2 } } }\) (‘n’ is the number of molecules per unit volume’ is the diameter of the molecule).

Answer 11.
a.

1. The area of the acceleration time graph gives change in velocity.
2. From a 1 graph, we can find instantaneous acceleration.
3. Slope of a 1 graph gives rate of change of acceleration.

c. Displacement = Area under graph
= Area of DOAB
= 14 × 3 × 12 = 18m

Answer 12.
a. Angular velocity \(\omega =\frac { 2\pi n }{ t } =\frac { 2\pi \times 6 }{ 3.14 } =1.2rad/s\)
b. Period of rotation in clockwise,

Answer 13.

Answer 14.
a. A radius of gyration of a body about an axis of rotation is defined as the distance from the axes to a point at which the whole mass of the body is assumed to be concentrated. It is denoted by K. \(K\sqrt { \frac { I }{ M } }\)
b: Fig (a), in this pose, a moment of inertia is larger than the fig (b).

Answer 15.

Answer 16.
a. Poles
b. Let ‘h’ be the height from the surface of the earth where the value of g is g/2.

c. Velocity is same ie, V_e = \(\sqrt { 2gR }\) Escape velocity is independent of the mass of the body that projected into space.

Answer 17.
a. Yes. Moon attracts every body towards its center.
b. Orbital velocity V₀ = \(\sqrt { Rg }\)
Escape velocity V_e = \(\sqrt { 2Rg } =\sqrt { 2 } { V }_{ 0 }\) % change in velocity

18. a. The forces acting on the sphere are

1. The weight of the sphere acting downward
2. A viscous force acting upward
3. Buoyant force acting upward.

An expression for terminal velocity:
Consider a small sphere of radius Y and mass placed on a surface of a highly viscous liquid contained in a jar. According to Stoke’s formula, a viscous force on the sphere moving with a terminal velocity ‘V and radius Y is given by F = 6πrnv where ‘n’ is the coefficient of viscosity of the fluid. Apparent weight of the sphere in a fluid is [ltex]\frac { 4 }{ 3 } \pi { r }^{ 2 }pg-\frac { 4 }{ 3 } \pi { r }^{ 3 }og[/latex]Where p is the density of the material of sphere a and that of the liquid At terminal velocity, \(\frac { 4 }{ 3 } \pi { r }^{ 3 }\left( p-\sigma \right)\)

b. Due to evaporation.

Answer 19.

Answer 20.
a. If a wave is produced at the open end of a tube it travels through the gas column and gets reflected at the closed end. At a certain height of tube the incident wave and reflected wave superpose each other and produce stationary wave and a sound is heard. This is called resonance. The open end always represents an antinode.
b. The first normal mode of vibration

Let l₁ be the wave length of standing have set up in the pipe corresponding to

The second normal mode of vibration (3rd harmonic, 1st overtone)

Let λ₂ be the wavelength of standing wave set up in the pipe corresponding to n = 2

Let λ₃ be the wave length of standing wave set up in the pipe corresponding to n = 3

The ratio of the first, second and third mode. V₁ : V₂ : V₃ = 1 : 3 : 5
c. All harmonics are present in open pipe, but in the closed pipe, only odd harmonics are present. So open pipe is preferred in a musical instrument.

Answer 21.

Let ‘mg’ be the weight of a vehicle moving with a speed ‘V around a banked road of radius ‘r’. Its normal reaction ‘ R’ can be resolved into 2 component R cos0 vertically upwards and R sinq towards the center of the curve. R sin0 gives necessary centripetal force while R cos0 balances the weight ‘mg’.

The direction of the frictional force Fs is such that the force resists the tendency of the car to skid to the outside of the curve. The horizontal component Fs cos0 is added to R sinq to provide a large centripetal force.

Substituting the value of R in equation (2)

divide the numerator and denominator by cosθ

Answer 22.

c. Satellite in a circular orbit of radius about 36,000 km around the earth in the equatorial plane with T = 24 hours is called geostationary satellites. They are mainly used for communication purpose, TV and Radio broadcasting and Weather forecasting.
Polar satellites are low altitude satellites that go around the poles of the earth in a north-south direction. Its time period is around 100 minutes and so it crosses any altitude many times a day. Its height above the earth is about 500800 km. In formation gathered from such satellites is extremely useful for remote sensing, meteorology as well as for environmental studies of the earth.

Answer 23.
a. Mercury barometer.
b. Pascal law. It states that an increase in pressure at one point of the enclosed liquid at rest is transmitted equally to every part of the liquid and to the wall of the container provided the effect of gravity is neglected.

In a hydraulic lift, two pistons are separated by the space filled with a liquid. A piston of small cross section A₁ is used to exert a force F₁ directly on the liquid. The pressure is P = \(\frac { { F }_{ 1 } }{ { A }_{ 1 } }\) is transmitted throughout the liquid to the larger cylinder attached with a larger piston of area A₂, which results in an upward force of P x A₂. Therefore, the piston is capable of supporting a large force (large weight of, say a car, or a truck, placed on the platform) F₂ = PA₂ = \(\frac { { F }_{ 1 }{ A }_{ 1 } }{ { A }_{ 1 } }\) By changing the force at A1, the platform can be moved up or down. Thus, the applied force has been increased by a factor of \(\frac { { A }_{ 2 } }{ { A }_{ 1 } }\) and this factor is the mechanical advantage of the device. The example below clarifies it.

c. Decreases, because of g decreases OR (g’ = g – a)

Answer 24.
a. Ideal gas or perfect gas

Carnot engine is an ideal heat engine. Main parts of Carnot engine are a source, working substance is an ideal gas which taken in a cylinder provided with a piston. The 3 sides of the cylinder are an insulator and the lower side is conducting, sink and an insulated stand. Adiabatic process in a car not cycle is performed in this insulated stand.
The four stages of the cycle are:

1. Isothermal expansion The cylinder containing the gas is placed in thermal contact with the source kept at high temperature (T₁,), It absorbs Q₁ amount of heat and expands, the expansion is isothermal. The initial pressure p₁ and volume V₁ of the gas change to p₂ and V₂. Thus the gas does a work W_AB

2. Adiabatic expansion (BC) The gas is placed on an insulating stand. Now no heat enters or leaves the system, the expansion is adiabatic. Pressure and volume change from p₂ and p₃ and V₂ to V₃. During the process, temperature falls to T₂. Work done by the gas is WBC.

3. Isothermal compression (CD) The cylinder is then placed on the sink at temperature T₂. Gas is compressed to reject some heat Q₂ to the sink. Since temperature T₂ remains constant, the compression is isothermal. Pressure and volume changes to p₄ and v₄ work done on the gas is WCD.

4. Adiabatic compression. The cylinder is again placed on the insulating stand for the completion of the compression process. Since no heat transfers or leaves the system, the compression is adiabatic. The gas attains the original pressure p₁ and volume v₁ at the end of this. Work done now is WDA.

Answer 25.
a.
i. Modulus of elasticity of gas is zero.
ii. Laplace corrected Newtons formula taking condensation and rare fraction as adiabatic process, v = \(\sqrt { \frac { VP }{ p } }\)

Plus One Physics Previous Year Question Papers and Answers

Kerala Plus One Physics Improvement Question Paper 2018

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures, and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Answer any four questions from question numbers 1 to 5. Each carries one score.

Question 1.
State TRUE or FALSE. “Some conservation laws are true for one fundamental force, but not for the others”.

Question 2.
The angle between

a. 45°
b. 90°
c. 60°
d. 180°

Question 3.
Three objects with a mass of 40 kg each are placed in a straight line 50 cm apart. What is the net gravitational force at the center object due to the other two?

Question 4.
Which one of the following relationships between the acceleration a and the displacement x of a particle involve simple harmonic motion?
a. a = 5x
b. a = -200 x²
c. a = -5x
d. a = 100 x³

Question 5.
The stress required to double the length of a wire of Youngs modulus Y is ………………


a. Y/2
b. 2Y
c. Y
d. 4Y

Answer any four questions from question numbers 6 to 10. Each carries two scores.

Question 6.
A car traveling at a speed 54 km/hr is brought to rest in the 90s. Find the distance traveled by car before coming to rest.

Question 7.
The parallelogram law is used to find the resultant of two vectors. Find the magnitude of the resultant of two vectors in terms of their magnitudes and angle between them.

Question 8.
Select the CORRECT alternative.
a. When a conservative force does positive
work on a body, the potential energy of the body ………………………

1. increases
2. decreases
3. remain unaltered

b. Work was done by a body against friction always results in a loss of its …………..

1. kinetic energy
2. potential energy

c. The rate of change of total momentum of a system of many-particle systems is proportional to the …………… on the system.

1. external force
2. a sum of the internal forces

d. The quantity which is conserved in an in an elastic collision of two bodies is ………….

1. total kinetic energy
2. total linear momentum

Question 9.
A steel wire of length 1.5 m and diameter 25 cm is loaded with a force of 98 N. The increase in the length of the wire is 1.5 × 10⁴ m. Calculate the tensile stress and the fractional change in length of the wire.

Question10.
According to the kinetic theory of gases, gas molecules are always in random motion.
a. State the law of equipartition of energy.
b. Write the average value of energy of a molecule for each vibrational mode.

Answer any four questions from question numbers 11 to 15. Each carries three scores.

Question 11.
Two parallel rail tracks run north-south. Train A moves north with a speed of 15 m/s and train B moves south with a speed of 25 m/s.
a. What is the velocity of B with respect to A?
b. What is the velocity of the ground with respect to B?
c. What is the velocity of a monkey running on the roof of the train A against its motion (with a velocity of 5 m/s with respect to the train A) as observed by a man standing on the ground?

Question 12.
An insect trapped in a circular groove of radius 12 cm moves along the groove steadily and completes 7 revolutions in 100s.
a. What is the linear speed of the motion?
b. Is the acceleration vector a constant vector? What is its magnitude?

Question 13.
A car arid a truck have the same kinetic energies at a certain instant while they are moving along two parallel roads.
a. Which one will have greater momentum?
b. If the mass of truck is 100 times greater than that of the car, find the ratio of loci of the truck to that of the car.

Question 14.
A girl rotates on a swivel chair as shown below.

a. What happens to her angular speed when she stretches her arms?
b. Name and state the conservation law applied for your justification.

Question 15.
A solid sphere of mass m and radius, R starts from rest and rolls down along an inclined plane of height h without slipping as shown below.

a. Calculate the kinetic energy of the sphere when it reaches the ground.
b. Find the velocity when it reaches the base.

Answer any four questions from question numbers 16 to 20. Each carries four scores.

Question 16.
A man jumping out of a slow moving bus falls forward.
a. This is due to
b. Which Newtons law gives the above concept? State the law.
c. What is the net force acting on a book at rest on the table?

Question 17.
To reduce friction and accident by skidding the roads are banked at curves.
a. What is meant by banking of roads?
b. Sketch the schematic diagram of a vehicle on a banked road with friction and mark the various forces.
c. Derive an expression for the maximum safe speed of a vehicle on a banked road with friction.

Question 18.
For a liquid-gas interface, the convex side has a high Pressure than the concave side.
a. Derive an expression for excess pressure inside a drop.
b. Which is better, washing of cloth in cool soap wafer or warm soapy water? Why?

Question 19.
Linear expansion is a change in length of an object with temperature.
a. Write the equation for the coefficient of j linear expansion.
b. Show that the coefficient of volume expansion is thrice its coefficient of linear ex! pension.
c. The absolute zero is ……………………………….
[ 273.15°C, 273.15K, 273.15°F, 0°C]

Question 20.
The simplest example of simple harmonic motion is the oscillations of a simple pendulum.
a. Derive an expression for the period of oscillation of a simple pendulum.
b. In a simple pendulum made of a metallic wire, what will happen to the period when the temperature increases? Give a reason.

Answer any four questions from question numbers 21 to 25. Each carries 5 scores.

Question 21.
a. The centripetal force depends on the mass of the body, velocity, and radius of a circular path. Find the expression for the centripetal force acting on the body using the principle of dimensional analysis. (Take constant k= 1)
b. When the planet Jupiter is at a distance of 824.7 million kilometers from the Earth, its angular diameter is measured to be 35.72” of an arc. Calculate the diameter of a Jupiter.

Question 22.
Satellites are objects which revolve around the earth.
a. The direction of revolution of a geosynchronous satellite is from
i. east to west
ii. west to east
iii. north to south
iv. south to north

b. Derive an expression for a total energy of an orbiting satellite.
c. What is the magnitude of the angular velocity for a geosynchronous satellite?

Question 23.
The flow of an ideal fluid in a pipe of a varying cross-section is shown below.

a. Write Bernoulli’s equation.
b. Find the speed of efflux using Bernoulli’s principle.
c. State Torricelli’s law.

Question 24.
The basic features of a device are schematically represented in the figure below.

a. Which type of device is this, a heat engine or a refrigerator?
b. Draw the indicator diagram and label the four processes in the Carnot cycle.
c. A steam engine delivers 5.4 × 108J of work per minute and services 3.6 × 109 J of heat per minute from its boiler. What is the efficiency of the engine? How much heat is wasted per minute?

Question 25.
A transverse harmonic wave on a string is described by y (x, t) = 3.0 Sin (36t + 0.018x + p/4)where ‘x’ and ‘y is in cm and’ is ins. The positive direction of’ is from left to right.
a. Is this a traveling wave or a stationary wave? If it is traveling, what are the speed and direction of its propagation?
b. What are its amplitude and frequency?
c. What is the least distance between two successive crests in the wave?

Answers

Answer 1.
True

Answer 2.
90°

Answer 3.
Zero

Answer 4.
c. a = -5x

Answer 5.
Y

Answer 6.

Answer 7.

Answer 8.
a. decrease
b. Kinetic energy
c. externally forced
d. Total linear momentum

Answer 9.

Answer 10.
a. Law of equipartition energy:
It states that in any dynamical system in thermal equilibrium, the energy is equally distributed amongst its various degrees of freedom and the energy associated with each degree of freedom per molecule is 1/2k_B T, where kB is Boltzmann’s constant and T is the absolute temperature of the system.

Answer 11.

Answer 12.

Answer 13.

Answer 14.
a. When the girl stretches her arm, according to a law of conservation of angular momentum the distance from the axis of rotation increases and so a moment of inertia increases and thereby angular speed decreases.
b. When no external torque acts on a system of particles, the angular momentum of the system remains constant.

Answer 15.

Answer 16.
a. Inertia
b. Newton’s First Law of Motion. “Everybody continues in its state of rest or uniform motion in a straight line unless some external unbalanced force acts on it”.
c. Zero

Answer 17.
c. Refer QNo. 23, Page No. 61

Answer 18.
a. Refer QNo. 25 (b), Page No. 61
b. Using hot water usually makes whatever is being treated expand or loosen so the dirt can be released easier. It is because hot water has lower surface tension than cold water(Temperature increases surface tension decreases).
This hot water is able to penetrate easily into the pores and wet the surface. In words, As we move along a streamline, Pressure energy + Kinetic energy + Potential energy, per unit volume = Constant.

Answer 19.

Answer 20.

An ideal simple pendulum is made of a heavy point mass body suspended from rigid support by an inextensible, weightless and perfectly flexible string. The body is free to oscillate in a vertical plane. When an undisturbed pendulum is in the position SO. S is the point of suspension and θ is the center of gravity of the bob.

The position SO is the equilibrium position. If the bob is slightly pulled aside and released, the pendulum oscillates between Q and P. Q & P represents the

position of a center of gravity of the bob in the displaced position during the oscillation, then the force at P is shown in the figure.

1. Weight mg of the bob acting vertically downwards.
2. The tension along the string T. ResoMng mg we get mg sinθ and mg cosθ as shown in the figure. Here mg cosθ balances the tension and mg sinθ acts tangentially at P hence, it acts as the restoring force.

Let SO = SQ = SP = I, OP = x Restoring force, F = -mg sinθ (restoring force tends to reduce angular displacement θ hence the -ve sign) If the displacement ‘x’ is small compared to ‘f, θ ¡s small hence sinθ = e Restoring force, F = -mgθ

b. As temperature increases the length of pendulum increases due to linear expansion. So the period of pendulum increases.

Answer 21.
a. Let F ∝ m^av^br^c or F = K m^av^br^c ………(1 where K is a dimensionless constant. Writing the dimensions of various quantities ¡n equation (1), we get

Comparing the dimensions of similar quantities on both sides, we get

This is the required expression for the centripetal force.

Answer 22.
a. West to east
b. The kinetic energy of the satellite in a circular orbit at height h from a surface of the earth with speedy is

The potential energy at distance (R+h) from the center of the earth is

c. A time period of geosynchronous satellite = 24hrs

Answer 23.

In words, As we move along a streamline, Pressure energy + Kinetic energy + Potential energy, per unit volume = Constant.

b.

If the top of the tank is also open to atmosphere, then P = P_a

The velocity V₂ is called velocity of efflux. This is same as the velocity of an object falling freely under gravity through a height h.

c. Torricelli’s theorem states that the speed at which fluid leaves the orifice at the bottom of a reservoir is the same as if an object is falling freely through the same height.

Answer 24.
a. Heat Engine

Answer 25.

Plus One Physics Previous Year Question Papers and Answers

Kerala Plus One Physics Previous Year Question Paper 2017

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures, and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Question 1.
Pick the odd one out among the following forces:
a. Gravitational force
b. Weak nuclear force
c. Viscous force
d. Electromagnetic force

Question 2.
The demonstration of conservation of angular momentum is schematically shown in the figures.

Identify the figure which has more angular velocity.

Question 3.
“Two systems in thermal equilibrium with a third system, are in thermal equilibrium with each other”. Identify the law given by the above statement.

Question 4.
A steel rod has a radius of 10 mm and a length of 1.0 m. A 100 kN force stretches it along its length. Calculate the elongation of the steel rod. [Young’s modulus of steel is 2.0 × 10¹¹ N/m².]

OR

A metal cube of side 10 cm is subjected to a; shear stress 10⁴ N/m². Calculate the rigidity: modulus, if the top of the cube is displaced by 0.05 cm with respect to its bottom.

Question 5.
Draw the schematic diagram of a hydraulic lift. Give its working principle.

Question 6.
Estimate the average thermal energy of the helium atom at a temperature of 27°C. [Boltzmann constant is 1.38 × 10^-23J/K.]

Question 7.
The graph below exhibits the anomalous expansion of water.


Based on the graph, explain how lakes freeze from the top to bottom rather than from bottom to top.

Question 8.
Match the following in three columns.

Question 9.
a. The figure below shows the ‘parallax method’ to measure the distance ‘D’ of a planet ‘S’ from the earth.


Mark the parallax angle ‘0’ in the figure. Explain how the distance ‘D’ can be measured.

b. Check whether the equation mv² = mgh is dimensionally consistent. Based on the above equation, justify the following statement. “A dimensionally correct equation need not be actually an exact equation”.

Question 10.
a. Choose the correct statement/statements related to uniform circular motion.
i. The acceleration in uniform circular motion is tangential to the circle.
ii. The acceleration in uniform circular motion is directed radially inwards.
iii. The velocity in uniform circular motion has constant magnitude.
iv. The velocity in uniform circular motion is directed radially inwards.
b. A particle is projected up into the air from the point with a speed of 20 m/s at an angle of projection 30°. What is the maximum height reached by it?

Question 11.
a. The escape speed from the surface of the earth is given by …………………..

b. An artificial satellite circulating the earth is at a height 3400 km from the surface of the earth. If the radius of the earth is 6400 km and g = 9.8 m/s², calculate the orbital velocity of the satellite.

Question 12.
a. Among the following, which are examples of simple harmonic motion?
i. The rotation of the earth about its axis.
ii. Vertical oscillations of a loaded spring.
iii. Oscillations of a simple pendulum.
iv. Uniform circular motion.
b. The displacement in simple harmonic motion can be represented as x(t) = A Cos(ωt+ Φ), where ‘Φ’is the phase constant. Identify and define ‘A’ and ‘co’ in the equation.

Question 13.
a. A transverse harmonic wave is described j by y=3.0 Sin (0.018 × + 36t), where ‘x’ and ‘y’ are in cm. The amplitude of this; the wave is

b. The figure below shows the fundamental mode or first harmonic in a stretched j string when a standing wave is formed ‘ in the string.

Draw the figure that shows the second; harmonic in the string. If ‘L’ is the length of the string and Vis the speed of the: wave in the string, what are the equations of first and second harmonic frequent:

Question 14.
An object released near the surface of the I earth is said to be in free fall. (Neglect the air resistance)

a. Choose the correct alternative from the clues given at the end of the statement. “Free fall is an example of accelerated motion”.

b. The incomplete table shows the velocity (υ) of a freely falling object in a time interval of 1 s. (Take g = 10 m/s²)

Complete the table and draw the velocity time graph.

c. Area under velocitytime graph gives.

Question 15.
The schematic diagram of the circular motion of a car on a banked road is shown in the figure.


a. If the centripetal force is provided by the horizontal components of ‘N’ and ‘F’ arrive at an expression for maximum safe speed.

b. The optimum speed of a car on a banked road to avoid wear and tear on its tyres is given by …………….

Question 16.
Energy of a body is defined as its capacity of doing work”.
a. The energy possessed by a body by virtue of motion is known as ………….
b. A body of mass 5 kg initially at rest is subjected to a horizontal force of 20 N. What is the kinetic energy acquired by the body at the end of 10 s?
c. State whether the following statement is TRUE or FALSE. “The change in kinetic energy of a particle is equal to the work done on it by the net force”.

Question 17.
The angular momentum of a particle is the rotational analogue of its linear momentum.

a. The equation connecting angular momentum and linear momentum are ……………

b. Starting from the equation connecting angular momentum and linear momentum, deduce the relation between torque and angular momentum.

Moment of inertia in rotational motion is analogous to mass in linear motion.

a. The moment of inertia of a circular disc about an axis perpendicular to the plane, at the center is given by ………….

b. State perpendicular axis theorem and by using the theorem, deduce the moment of inertia of the circular disc about an axis passing through the diameter.

Question 18.
A region of streamline flow of an incompressible fluid is shown in the figure.

a. By considering mass conservation in the fluid flow, arrive at the ‘equation of continuity’.

b. The onset of turbulence in a fluid is determined by ‘Reynolds number’, given as …………….

Schematic diagram of capillary rise in a narrow tube is shown in the figure.

a. Arrive at an expression for capillary height ‘h’ in terms of the surface tension of the liquid.

b. On the surface of the moon, the liquid in a capillary tube will rise to the ……………..

i. same height as on earth,

ii. less height as on earth

iii. more height than that on earth

iv. infinite height.

Answers

Answer 1.
Viscous force (Not a fundamental force in nature)

Answer 2.
Figure 2. (Law of a moment of inertia) When the man stretched his arm, according to a law of conservation of angular momentum the distance from the axis of rotation increases and
so a moment of inertia increases and thereby angular speed decreases.

Answer 3.
Zeroth law of thermodynamics. 0 .05/10

Answer 4.

OR

Answer 5.
Pascal’s law is the working principle behind the hydraulic lift. Pascal’s law states that The pressure in a fluid at rest is same at all points if we ignore gravity.

If the pressure in a liquid is changed at a particular point, the change is transmitted to the entire liquid without being diminished in magnitude. The pressure exerted at any point on an enclosed liquid is transmitted equally in all directions.

Construction: It is a simple application of Pascal’s law. There are two cylinders C₁ and C₂ of cross-sectional areas A₁ and A₂ connected by a pipe. Pistons are fitted in both cylinders. The load to be lifted is kept on the platform of the piston with more area (A₂>A₁). The cylinders and pipe contain a liquid.

Working: A force is applied on the smaller piston. Then pressure exerted on the liquid is, \(P=\frac { { F }_{ 1 } }{ A }\) According to Pascal’s law, the same pressure ‘P’ is transmitted to the larger piston. Force on larger piston ¡s

Hence by making the ratio A₂/A₁ large, very heavy loads like cars can be lifted by using a small force.

Answer 6.

Answer 7.
When water is cooled from 4°C to 0°C, it expands. So ¡ce at 0°C ¡s less dense (more volume) than water at 4°C. When lake starts cooling water at the top reaches 4°C and sinks to the bottom due to high density. This continues till whole water reaches 4°C. Now when the temperature decreases to zero water on the top becomes ice which is less dense than the water below. So it does not sink.

Answer 8.

Answer 9.

To measure the distance D of a faraway planet S by the parallax method, we observe it from two different positions (observatories) A and B on the earth, separated by distance AB = b at the same time as in fig. We measure the angle between the two directions along which the planet is viewed at these two points. The ∠ASB represented by symbol 0 is called the parallax angle or parallactic angle.

As the planet is very far away, \(\frac { { b } }{ D } <<1\) and therefore, O is very small. Then we approxi mately take AB as an arc of length b or a circle with centre at S and the distance D as the radius AS = BS. So that AB = b = DO where O is in radians \(D=\frac { { b } }{ \theta }\)

b. mv² = mgh, takig dimension on both sides
[M] [LT^-1]² = [M] [LT^-1] [L]
[ML²T²] = [M¹L²T²]
The given equation is dimensionally cor rect. This is not the exact equation, which is mgh. Since the fraction ½ has no dimension, the complete consistency can’t be checked.

Answer 10.

Answer 11.

Answer 12.
a. (ii) and (iii)
b. A is the amplitude and w is the angular frequency.

Amplitude is the maximum displacement of the oscillating particle on either side of its mean position. Thus X_mxv = + A Angular frequency is equal to the product of the frequency of the body and 27t.

Answer 13.
a. 3 cm
b.Fundamental mode (or) First harmonic If the string is plucked in the middle and released, then it vibrates ¡n one segment with nodes at its ends and an antinode in the middle.

This is the lowest frequency with which string vibrates.

Second harmonic If the string is pressed in the middle and plucked at one-fourth of its length, then the string vibrates in two segments.

Answer 14.
Uniformly.

c. Displacement

Answer 15.
a. To avoid skidding and damage to tires of vehicles, the outer part of a road is slightly raised than the inner part. This is known as banking of roads.

1. The weight of the car vertically downwards.
2. Normal reaction R acting normal to the road.
3. Frictional force acting parallel to the road. Since there is no vertical acceleration,
R cosθ = mg + Fsinθ
or Rcosθ Fsinθ = mg …(1)
Now for maximum speed, F = μ, R
The centripetal force is provided by horizontal components of R and F as shown in the figure.

Answer 16.

Answer 17.

b. This theorem is good for flat bodies which means, thickness much less than length and breadth. The theorem states that “the moment of inertia of a planar body about an axis perpendicular to its plane is equal to the sum of moments of inertia about two mutually perpendicular axes passing through the same point, lying on the plane”. Moment of inertia about diameter can be found using perpendicular axis theorem.

Answer 18.
a. Consider a nonviscous (no internal friction) and incompressible (density constant during flow) liquid flowing steadily between the sections P and R of a pipe of varying cross-section. Let the area of a cross section at P be A, and that at R be A₂. Let the speed of fluid be v₁ at P and v₂ at R.

As, m = volume × density = area of cross-section × length × density Mass of fluid that flows through P in time Δt, m₁ = A₁v₁P₁ Δt
Mass of fluid that flows through R in time At, m2 = A₂V₂P₂ Δt
By conservation of mass, m1 = m₂
A₁v₁P₁ Δt = A₂v₂p₂ Δt and P₁ = p₂ (incompressible fluid)
A₁v₁= A₂v₂
The product of the area of crosssection and the speed remains the same at all points of a tube of flow. This is called the equation of continuity and expresses the law of conservation of mass in fluid dynamics.
b. iii \(\frac { p\upsilon d }{ n } =Re\)

OR

a. When a clean capillary tube is dipped in a liquid, which wets it, the liquid immediately rises in the tube. This is called capillary rise.

Consider a capillary tube of radius ripped vertically in a liquid of density p and surface tension a. The meniscus of the liquid inside the tube is concave. Thereby the liquid rises through the tube to some height. Let ‘ R’ be the radius of the meniscus, 0 be the angle of contact and h the height of the liquid column in the tube with respect to the level of a liquid outside.

Here the hydrostatic pressure exerted by the liquid column becomes equal to the excess pressure p. Therefore at equilibrium, we have p = hpg

b. iii. more height than that on earth

Plus One Physics Previous Year Question Papers and Answers

Kerala Plus One Physics Previous Year Question Paper 2018

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before you answering.
• Calculations, figures, and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• Give equations wherever necessary.
• Electronic devices except non-programmable calculators are not allowed in the Examination Hall.

Answer any four questions from question numbers 1 to 5. Each carries one score.

Question 1.
The branch of Physics, that was developed to understand and improve the working of heat engines is …………
a. Optics
b. Thermodynamics
c. Electronics
d. Electrodynamics

Question 2.
State the theorem of parallel axes on a moment of inertia.

Question 3.
Select a TRUE statement from the following:
a. A year and light year have the same dimensions.
b. The intensity of the gravitational field has the same dimensions as that of acceleration.
c. One angstrom is the mean distance between sun and earth.
d. Parsec is a unit of time.

Question 4.
If the zero of potential energy is at infinity, the total energy of an orbiting satellite is negative of its …………….. energy.

Question 5.
What is the time period of a second’s pendulum?

Answer any five questions from question numbers 6 to 11. Each carries two scores.

Question 6.
Using a suitable velocity-time graph, derive the relation x = v₀t+ ½ at².

Question 7.
A boy throws a ball of mass 200 g with a velocity 20 ms^-1 at an angle of 40° with the horizontal. What is the kinetic energy of the ball at the highest point of the trajectory?

Question 8.
Write the work done in each of the following cases as zero, positive or negative.
a. Work was done by centripetal force in circular motion.
b. Work was done by friction.
c. Work was done by the gravitational force on a freely falling object.
d. Work was done by the applied force in lifting an object.

Question 9.
Derive an It escapes velocity of an object from the surface of a planet.

Question 10.
A typical stress-strain graph of a metallic wire is shown below.


a. Write the name of the point B labeled in the graph.
b. For materials like copper, the points D and E are ………………. (close/far apart).

Question 11.
The terminal velocity of a copper ball of radius 2.0 mm falling through a tank of oil at 20°C is 6.5 cm s^-1. Calculate the viscosity of the oil at 20°C.
(Hints: Density of oil is 1.5 × 10³ kg m^-3, a density of copper is 8.9 × 10³ kg m^-3.)

Answer any live questions from question numbers 12 to 17. Each carries three scores.

Question 12.
A body falling under the effect of gravity is said to be in free fall.

a. Draw the velocity-time graph for a freely falling object.

b. Define uniform acceleration.

c. From the given figures, identify the figure which represents uniformly accelerated motion.

Question 13.
A gun moves backward when a shot is fired from it.
a. Choose the correct statement.
i. The momentum of the gun is greater than that of the shot.
ii. The momentum acquired by Jche gun and shot have the same magnitude.
iii. Gun and shot acquire the same amount of kinetic energy.
b. A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is 80 m/s, what is the recoil speed of the gun?

Question 14.
Acceleration due to gravity decreases with depth.
a. Prove the above statement by deriving the proper equation.
b. Using the equation, show that acceleration due to gravity is maximum at the surface and zero at the center of the earth.

Question 15.
A device used to lift automobiles is shown in the figure.


a. Write the name of the device

b. In the situation shown in the figure, a mass of the car is 3000 kg and area of the piston carrying it is 425cm2. What pressure is to be applied to the smaller piston?

Question 16.
Based on the kinetic theory of gases, derive an expression for the pressure exerted by an ideal gas.

Question 17.
When 0.15 kg of ice at 0°C is mixed with 0.30 kg of water at 50°C in a container, the resulting temperature is 6.7°C. Calculate the latent heat of fusion of ice. Given specific heat capacity of water 4186 J kg^-1K^-1.

Answer any four questions from question numbers 18 to 22. Each carries four scores.

Question 18.
The accuracy in measurement depends on the limit or the resolution of the measuring instrument.
a. State whether the above statement is TRUE or FALSE.
b. A physical quantity P is related to four observables a,b,c, and d as P= The percentage errors in measurements of a,b,c, and d are 1%, 3%, 2%, and 3% respectively. What is the percentage error in the measurement of P?

Question 19.
A stone tied to the end of a string 80 cm long is whirled in a horizontal circle with a constant speed.
a. What is the angle between velocity and acceleration at any instant of motion?
b. If the stone makes 14 revolutions in 25 s,
what is the magnitude of the acceleration of the stone?

Question 20.
a. If \(\xrightarrow { A }\) is perpendicular to \(\xrightarrow { B }\), what is the
value of \(\xrightarrow { A }\).\(\xrightarrow { B }\)?
b. Find the angle between the force \(\xrightarrow { F }\) = (\(3\hat { i }\) + \(4\hat { j }\) –\(5\hat { k }\))N and displacement \(\xrightarrow { d }\) = (\(5\hat { i }\) + \(4\hat { j }\) + \(3\hat { k }\))m.

Question 21.
Schematic diagram of a device is shown below.

a. Write the equation for the efficiency of the device.

b. Write the name of the four processes in the working cycle of the device

c. If T₁ =100°C, T₂ = 0°C, and Q₁ = 4200 J find the value of Q₂

Question 22.
a. Which one of the following relationships between the acceleration (a) and the displacement (x) of a particle involves simple harmonic motion?

i. a = 0.7 x
ii. a = 200 x
iii. a = 10x
iv. a=100x
b. A simple harmonic motion is represented as x = A cost. Obtain the expression for velocity and acceleration of the object and hence prove that acceleration is directly proportional to the displacement.

Answer any three questions from question numbers 23 to 26. Each carries five scores.

Question 23.
a. What is the condition for the equilibrium of concurrent forces?

b. A mass of 6 kg is suspended by a rope of length 2m from the ceiling. A force of 50 N in the horizontal direction is applied at the midpoint P of the rope, as shown. What is the angle, the rope makes with the vertical in equilibrium? (Take g=10 ms 2). Neglect the mass of the rope.

c. What will be the angle made by the rope with the vertical if its length is doubled?

Question 24.
a. Write the equation connecting torque with force.

b. A meter stick is balanced at its cecenter50 cm). When two coins, each of mass 5 g, are put one on the top of the other at the 12 cm mark, it is found to be balanced at 45 cm. What is the mass of the stick?

c. Derive the relation connecting torque with angular momentum.

Question 25.
a. Water rises up in a narrow tube in spite of gravity. This phenomenon is called…
b. Derive an expression for the height of water in the tube in terms of the radius of the tube and surface tension of the liquid.
c. Water with detergent dissolved in it should have an angle of contact. (Small/large)

Question 26.
The fundamental mode of vibration of a stretched string is shown below.


a. Draw the second and third harmonics.
b. Prove that frequencies produced in the string are in the ratio of 1: 2: 3.
c. Let the fundamental frequency is 45 Hz and the length of the wire is 87.5 cm. If the linear density of the wire is 4.0 × 10² kg/m. Find the tension in the string

Answers

Answer 1.
Thermodynamics

Answer 2.
This theorem is good for any shape. The moment of inertia of the body about any axis is equal to the sum of a moment of inertia of a parallel axis passing through the center of mass and product of its mass of the body and square of the distance between the two parallel axes. I = I_g + Ma²

Answer 3.
b

Answer 4.
Kinetic energy

Answer 5.
T = 2sec

Answer 6.

The area under the velocity-time graph gives the displacement of the body. Displacement, x = area OABD x = area of triangle ABC+ area of rectal

Answer 7.
At the top V = 0, V_x = ucosθ

Answer 8.
a. Zero
b. Zero or negative ( 0 for static)
c. Positive
d. Positive

Answer 9.
The total work done to move a body of mass’m’ from the surface of the earth (r=R) to
infinity (r = ) is given by, \(W=\frac { GMm }{ R }\)
Let v be the velocity of the body, then K.E of the body, when projected, is K = 1/2 mv² The body can escape from the gravitational pull of earth only if the KE is greater than or equal to the work done in overcoming the gravity.

Answer 10.
a. Elastic limit or Yield point
b. Far apart (Copper is malleable)

Answer 11.

Answer 12.

b. Equal change in velocity in an equal time interval.
c. Fig(3)

Answer 13.

Answer 14.

Answer 15.
a. Hydraulic Lift

Answer 16.

Consider a gas contained in a cubical vessel of side 7 and volume V = B. Let there be ‘n’ molecules per unit volume of the gas, each of masses’. Hence the total mass of the gas in the vessel M = nm × v The molecules are having random velocities and since the motion is not under a force. Consider such a molecule moving with a velocity V along X-direction as shown in the figure. As it moves in the positive X-direction it undergoes elastic collision and is a bounce from the wall O’A’B’C’. The momentum of the molecule before collision = mv

Momentum after collision=mv (rebounding) Change in momentum= mv (mv) = 2mv Hence the change of momentum imparted to the wall = 2mv For this molecule to undergo the next collision with the same wall it has to travel a distance 2l. The time to travel this distance by the molecule is given by t = 2//v Number of collision per second with this wall =\(\frac { l }{ t }\) = \(\frac { l }{ 2l }\)

According to Newton’s second law change in momentum per second = force on the wall. i.e., the thrust by 1 molecule. Taking all the ‘n’ molecules in a unit volume of the vessel, each will be travelling in x, y, z direction on the average. Let V₁ V₂, V₃, ………… V_n be the velocities of n molecules. Then average value of velocity square is shown as below.

where \(\vec { V }\) is called the root mean square velocity (rms velocity of the molecule), rms velocity of a gas molecule is defined as the square root of the mean of the squares of the velocities of the gas molecules. It is given by

Answer 17.

Answer 18.

Answer 19.

Answer 20.

Answer 21.

b. Isothermal expansion Adiabatic expansion Isothermal compression Adiabatic compression

Answer 22.

Answer 23.
a. Vector sum of all the forces = 0

c. All the fores are independent of length (for massless string)

Answer 24.

Differentiating with respect to line

Answer 25.
a. Cappilarity/Capillary rise
b. When a clean capillary tube is dipped in a liquid, which wets it, the liquid immediately rises in the tube. This is called capillary rise.

Consider a capillary tube of radius rdip ped vertically in a liquid of density p and surface tension a. The meniscus of the liquid inside the tube is concave. Thereby the liquid rises through the tube to some heightLet ‘R’ be the radius of the meniscus, 0 be the angle of contact and h the height of the liquid column in the tube with respect to the level of liquid outside.

Here the hydrostatic pressure exerted by the liquid column becomes equal to the excess pressure p. Therefore at equilibrium, we have


c. Small

Answer 26.

In an open tube, both ends are open. At both ends, antinodes are formed. The mode of vibration of the open organ pipe are

Plus One Physics Previous Year Question Papers and Answers

Kerala Plus One Maths Model Question Paper 4

Time Allowed: 2 1/2 hours
Cool off time: 15 Minutes
Maximum Marks: 80

General Instructions to Candidates :

• There is a ‘cool off time’ of 15 minutes in addition to the writing time .
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read instructions carefully .
• Read questions carefully before you answering.
• Calculations, figures and graphs should be shown in the answer sheet itself.
• Malayalam version of the questions is also provided.
• .Give equations wherever necessary.
• Electronic devices except non programmable calculators are not allowed in the Examination Hall.

Questions 1 to 7 carry 3 scor each. Answer any 6.

Question 1.
Consider the Venn-diagram given below.

Question 2.
For any triangle ABC, prove that

Question 3.
Consider the complex number z = 3 + 4i
a. Write the conjugate of z.
b. Verify that z z =|z|²

Question 4.
a. Solve the inequality

b. Represent the solution in real line

Question 5.
4 cards are drawn from a wellshuffled pack of 52 cards.
a. In how many ways can this be done?
b. In how many ways can this be done if all 4 cards are of the same colour?

Question 6.
Consider the equation of the ellipse 9x²+ 4y² = 36. Find
a. Focii
b. Eccentricity
c. Length of latus rectum

Question 7.

Questions from 8 to 17 carry 4 scor each. Answer any 8.

Question 8.
Consider A = {x : x is an integer, 0 < x ≤ 3}
a. Write A in roster form.
b. Write the power set of A.
c. The number of proper subsets of A =
d. Write the number of possible relations from A to A.

Question 9.
Consider the statement

a. Show that P(1) is true.
b. Prove that P(n) is true for all n ∈ N using principle of mathematical induction.

Question 10.
Consider the complex number, z =
\(\frac { 1 + 3i }{ 1 + 2 i}\)
a. Write z in the form a + ib.
b. Write z in polar form

Question 11.
Solve the following inequalities graphically

Question 12.
a. How many 3 letter words with or without meaning can be formed using 26 letters in English alphabet, if no letter is repeated?
b. Find the number of permutations of letters of the word MATHEMATICS
c. How many of them begin with the letter C?

Question 13.
Consider the figure given below. A (3, 0) and B (0, 2) are two points on axes. The line OP is perpendicular to AB.

a. Find the slope of OP.
b. Find the co-ordinates of the point P.

Question 14.
Equation of the parabola given in the figures is y= 8x.

a. Find the focus and length of latus rectum of the parabola.
b. The latus rectum of the parabola is a chord to the circle centered at origin as shown in the figure. Find the equation of the circle.

Question 15.
Let L be the line x – 2y+3 = 0.
a. Find the equation of the line L₁ which is parallel to L and passing through (1, -2).
b. Find the distance between L and L₂.
c. Write the equation of another line L₂ which is parallel to L, such that the distance from origin to L and L₂ are the same.

Question 16.
Consider the points A (3, 2, 01).
a. Write the octant in which A belongs to
b. If B (1, 2, 3) is another point in space, find distance between A and B.
c. Find the coordinates of the point R which divides AB in the ratio 1 : 2 internally.

Question 17.
a. Write the contrapositive of the statement:
P : If a triangle is equilateral, then it is isosceles.
b. Prove by the method of contradiction ‘ √3 is irrational’

Questions from 18 to 24 carry 6 score each. Answer any 5.

Question 18.
a. If A = {a, b} write A x A x A
b. If R = {(x,x³) : x is a prime number, less than 10}. Write R in roster form.
c. Find the domain and range of the function f (x) = 2+ √x-1

Question 19.
a. The minute hand of a watch is 3 cm long. How far does its tip move in 40 minutes? (Use π = 3.14).
b. Solve the trigonometric equation sin 2x-sin 4x + sin 6x = 0.

Question 20.
a. Find the sum of all 3 digit numbers which are multiples of 5.
b. How many terms of the GP 3, 3², 3³, …. are needed to give the sum 120?
c. Find the sum of first n terms of the series whose n* term is n(n + 3).

Question 21.
a. Expand using binomial theorem,
b. Find (a+b)4 – (a-b)⁴
c. Hence find (√3 + √2)4 -(√3-√2)4

Question 22.
a. Find the derivative of the function y = 1/x from first principles.
b. Differentiate f(x) = ,\(\frac { cos x }{ 1 + sinx }\)
with respect to x.

Question 23.
Calculate the mean deviation about median for the following data.

Question 24.
Consider a bag containing 3 red balls R₁, R₂, R₃ and 2 black balls B₁, B₂, which are identical. 2 balls are drawn simultaneously at random from the bag.
a. Write the sample space of the random experiment.
b. Write the event
A : Both balls are red B : One is red and one is black
c. Show that A and B are mutually exclusive
d. Find P(A) and P(B)

Answers

Answer 1.
a. A’= {5, 6, 7, 8, 9}
B’= {1, 2, 7, 8, 9}
(A ∩ B)’ = {l,2,5,6, 7, 8, 9}
b. LHS = (A ∩ B)’ = {1,2, 5, 6, 7, 8,9}
RHS=A’∪B’= {1,2, 5, 6, 7, 8, 9}
∴(A∩B)’= A’∪B’

Answer 2.

Answer 3.
a. conjugate of z = 3 + 4i = 3 – 4i
b. z z̄ = (3+4i) (3-4i) = 9 – 16i² = 9 – (-16) = 25
\({ \left| z \right| }^{ 2 }={ \left( \sqrt { { 3 }^{ 2 }+{ 4 }^{ 2 } } \right) }^{ 2 }={ \left( \sqrt { 25 } \right) }^{ 2 }=25\)
\(\Rightarrow z=\bar { z } ={ \left| z \right| }^{ 2 }\)

Answer 4.

Answer 5.
a. No. of ways = ⁵²C₄ = 270725
b. No. of ways of all cards of the same colour = ²⁶C₄+²⁶C₄ = 2 x ²⁶C₄ = 29900

Answer 6.
The standard form of the ellipse is \({ x }^{ 2 }+{ y }^{ 2 }\) = 1, is an ellipse whose major axis is on the y-axis.
a = 3, b = 2
c = \(\sqrt { { a }^{ 2 }-{ b }^{ 2 } } \) = \(\sqrt { 9-4 } \) = √5
a. Focii = (0, ± c) = (0, +√5)
b. Eccentricity = c/a = √5/3
c. Length of latus rectum = \(\frac { { 2b }^{ 2 } }{ a } =\frac { { 2\times 2 }^{ 2 } }{ 3 } =\frac { 8 }{ 3 } \)

Answer 7.

Answer 8.
a. A = {1, 2, 3}
b. Power set of A = P(A)={ 1,2,3}, {1,2}, {1,3}, {2,3}, {1}, {2}, {3}, φ}
c. No. of proper subject of A = 2ⁿ-1 = 2³-1 = 7
d. No. of relations from A to A = 2^mxm=2^3×3 = 512

Answer 9.

Answer 10.

Answer 11.

Answer 12.
a. No. of words = ²⁶P₃ = 15600
b. The word MATHEMATICS has

c. If the letter C is fixed first, the remaining 10 letters can be permuted as

Answer 13.
a. Slope of OP

b. Equation of OP is

Answer 14.
Equation of parabola is y² = 8x ⇒ a = 2
a. Focus = (a, 0) = (2, 0)
Length of latus rectum = 4a = 4 x 2 = 8
b. Coordinates of A is (a, -2a) = (2, -4) and that of B iss (1, 2a) = (2, 4)
∴ Radius of the circle

Answer 15.
a. Equation of L is x-2y + 3 = 0

its given that distance from origin to L and L₂ are same. We have,

Answer 16.

Answer 17.
a. Contrapositive statement: If a triangle is not isosceles, then it is not equilateral.
b. Let us assume that √3 be rational ∴√3 = a/b, where a and b are co-prime, i.e., a and b have no common factors othe than 1.
3b² = a² ⇒ 3 divides a.
∴ there exists an integer ‘k’ such that a = 3k
∴ a² = 9k² ⇒ 3b² = 9k² ⇒b² = 3k² ⇒3divides b.
i.e., 3 divides both a and b, which is contradiction to our assumption that a and b have no common factor.
∴ our supposition is wrong.

Answer 18.
a. Ax Ax A={(a, a, a), (a, a, b), (a, b, a),
(a, b, b), (b, a, a), (b, a, b), (b, b, a), (b, b, b)}
b. R = {(2, 8), (3, 27), (5, 125), (7, 343)}
c. Domain=[1, ∞ ),{x/x ≥ 1}
Range = [2,∞), {y/y ≥ 2}

Answer 19.
a. The required distance moved

Answer 20.

Answer 21.

Answer 22.

Answer 23.

Answer 24.

Plus One Maths Previous Year Question Papers and Answers