Plus Two

Kerala State Board New Syllabus Plus Two Botany Previous Year Question Papers and Answers.

Kerala Plus Two Botany Previous Year Question Paper March 2018 with Answers

Time: 1 Hour
Cool off time : 10 Minutes
Maximum : 30 Score

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• You are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.                  ,
• 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.

I. (Questions 1 to 2): Answer Alt questions. Each question carries 1 score. (2 × 1 = 2)

Question 1.
Select the disease resistant variety of Bhindi produced by rotation breeding.
a) Himgiri
b) Parbhani Kranti
c) Pusa Gaurav
d) Pusa Komal
Answer:
b) Parbhani Kranti

Question 2.
Under unfavourable conditions many zooplankton species in lakes and ponds are known to enter a stage of suspended development. Name that stage.
Answer:
Diapause

II. (Questions 3 to 15) : Answer any eleven questions from the following. Each question carries 2 Scores. (Scores : 11 × 2 = 22)

Question 3.
Ozone acts as a shield for absorbing ultraviolet radiation from the sun.
a) Name the region of atmosphere where ozone is seen.
b) Write the unit used to measure ozone layer
Answer:
a) Troposphere or Stratosphere
b) Dobson

Question 4.
Match the following organisms to their life span:

Answer:

Question 5.
The DNA fragments can be separated using get electrophoresis.
a) Name the gel used in this technique.
b) Write the name of technique used to remove the DNA from the gel.
Answer:
a) Agarose
b) Elution

Question 6.
Observe the following figure:

a) Identify the figure
b) What does (i) tet^R (ii) rop (iii) ori denote?
Answer:
a) Cloning vector – pBr322
b) i) tet^R – tetracycline resistant gene
ii) rop – Gene codes for proteins involved in the replication of plasmid
iii) ori – Orgin of replication

Question 7.
Synergids have special cellular thickening at micropylar tip. Write the name and function of this structure.
Answer:

• Filiform apparatus
• It guides pollen tube into synergid

Question 8.
Controlled breeding experiments can be carried out using artificial insemination. What are the advantages of this process?
Answer:
The semen is collected from the male partner and injected into the reproductive tract of selected female. The collected semen can be stored in freezing state and used at later date.

Question 9.
Bio-fortification is a practical approach to improve the public health. Name any four such crops released by IARI.
Answer:
Vitamin A enriched carrot and spinach
Protien enriched beans – lablab

Question 10.
The products of ecosystem processes are named as ecosystem services. List out any four such services.
Answer:

1. Ecosystems purify air and water
2. Mitigate droughts and floods
3. Cycle nutrients
4. Provide wildlife habitat

Question 11.
In 1990’s Delhi ranked fourth among the most polluted cities of the world. What are the parallel steps taken to reduce vehicular pollution?
Answer:

1. Avoid the use of old vehicles
2. use of unleaded petrol
3. use of low-sulphur petrol and diesel
4. use of catalytic converters in vehicles

Question 12.
Increase in the level of green house gases leads to global warming. How can it be controlled?
Answer:
Global warming is controlled by

1. cutting down use of fossil fuel
2. improving efficiency of energy usage
3. reducing deforestation
4. planting trees

Question 13.
Genetically modified plants have been used in many ways. Give any four advantages of such plants.
Answer:

1. crops are tolerant to abiotic stresses
2. reduced reliance on chemical pesticides
3. helped to reduce post harvest losses.
4. increased efficiency of mineral usage by plants

Question 14.
In 1943 American Company Eli lilly produced human insulin artificially. Write down the method followed in this technique.
Answer:
American company Eli Lilly prepared Genetically engineered insulin. Steps are given below

1. Isolation of desired genes.
2. Insertion of desired Genes into plasmids of E. coli.
3. Introduction of plasmids into E coli cells.
4. Culture of E coli cells.
5. After this, a polypeptide chains A and B are separated and connected together by disulphide linkages.

Question 15.
Pyramid of energy is never been inverted, why?
Answer:
When energy flows from one trophic level to the next higher trophic level, energy is lost as heat. This is based on 10 % law.

III. (Questions 16 to 18) : Write any two from the following questions. Each question carries 3 Scores. (Scores : 2 × 3 = 6)

Question 16.
Meloidogyne incognitia is a nematode parasite infects the root of tobacco plants. It’s infection can be prevented by biotechnological methods.
a) Name the strategy.
b) Explain the principle behind this strategy.
Answer:
a) RNA interference

b) Nematode Meloidegyne incognitia infects the roots of tobacco plants and reduces the yield. Nematode-specific genes are introduced into the host plant by Agrobacterium vectors, it produce both sense and anti-sense RNA in the host cells that initiated RNAi and prevent the translation of the specific mRNA of the nematode.

Question 17.
The following graph shows two types of population growth curves:

a) Name the growth curves.
b) What does ‘K’ stand for?
Answer:
a) Exponential growth (J shaped growth curve)
Logistic growth (S shaped growth curve)

b) Carrying capacity

Question 18.
In Angiosperms female gametophyte is known as embryo sac. Explain it’s development.
Answer:
A single megaspore mother cell differentiates in the micropylar region of the nucellus. It undergoes meiotic division to form four megaspores.

Out of four, three degenerates and one megaspore is functional. The functional megaspore undergoes three repeated mitotic division to form 8 nucleate and 7 celled embryosac (female gametophyte).

HSE Kerala Board Syllabus Plus Two Previous Year Model Question Papers and Answers Pdf HSSLive Free Download in both English medium and Malayalam medium are part of Plus Two Kerala SCERT. Here HSSlive.Guru have given Higher Secondary Kerala Plus Two Previous Year Sample Question Papers with Answers based on CBSE NCERT syllabus.

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Kerala Plus Two Chemistry Model Question Paper 5

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 of 2 hrs.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• Read the instructions carefully.
• 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 from 1 to 7 carry 1 score. Answer any 6 questions.

Question 1:
The edge length and axial angles of a unit cell are a = b = c and α = β = γ = 90° respectively. Identify the type of Crystal System.

Question 2:
Name the polymer used for non-stick surface coated utensils

Question 3:
Which of the following forms colored compounds.

i. Sc³⁺
ii. Cr²⁺
iii. Zn³⁺
iv. Cu⁺
[Atomic number Sc – 21, Cr – 24, Zn – 30, Cu – 29]

Question 4:
The rate expression of a reaction is Rate = K [A]^{\(\frac { 1 }{ 2 }\)} [B]^{\(\frac { 1 }{ 2 }\)}. Calculate its overall order.

Question 5:
Among the following amines, identify the one that does not reach with Hinsberg reagent

i. C₂H₅NH₂
ii. (CH₃)₂NH
iii. (C₂H₅)₂NH
iv. (CH₃)₃N

Question 6:
The Carbohydrate, that is known as ‘animals starch’ is ………

Question 7:
Name the class of drug used for the treatment of stress and mental diseases.

Questions from 8 to 20 carry 2 score. Answer any 10 questions.

Question 8:
Write the names and structure of the monomers of the polymer Buna – S

Question 9:
Calculate the packing efficiency in body centred cubic structure.
[Given that r = \(\frac { \sqrt { 3 } }{ 2 }\)a, Where ‘r’ is the radius of sphere and ‘a’ is the edge length of unit cell]

Question 10:
Write one method for the preparation of sulphur dioxide. How is its presence detected?

Question 11:
Write the IUPAC names of following com-pounds.

(a) K₃[Fe(CN)₆]
(b) CO[Cl₂(en)₂Cl

Question 12:
Define Van’t Hoff factor ‘i’. What would be the value of ‘i’ for a dilute solution of K₂SO₄ in water?

Question 13:
By taking ethyl bromide as starting material, prepare ethyl iodide and ethyl fluoride.

Question 14:
Write the complete reaction representing the disproportionation of benzaldehyde.

Question 15:
Vapour pressure of water at 293 K is 17.535 mm Hg. Calculate the vapour pressure of water at 293 K when 25 g of glucose is dissolved in 450 g of water.

Question 16:
Name the products of hydrolysis of sucrose is not a reducing sugar.

Question 17:
Tetiary buty bromide react with aqueous NaOH to give tertiary butyl alcohol proceeds via S_N1 reaction. Write the mechanism of the reaction.

Question 18:
Give the structures of A and B in the following reaction.

Question 19:
Match the following

Question 20:
Write a simple chemical test to distinguish ethanal from propanone.

Questions from 21 to 29 carry 3 score. Answer any 6 questions.

Question 21:
The resistance of a 0.5 M solution of an electrolyte enclosed between two platinum electrode 1.5 cm apart and having an area of 2.0 cm² was found to be 30Ω. Calculate the molar conductivity of the solution.

Question 22:
write notes on different allotropic forms of phosphorous.

Question 23:
Integrated rate equation for a first order reaction.

a. Derive an expression for half life of first order reaction

b. Find the half life of first order reaction having rate constant K = 5.5 x 10^-14S^-1

Question 24:
What are adsorption isotherms? Write the Freundlich absorption isotherm equation and plot agraph based on it.

Question 25:
Describes the steps involved in the manufacture of sulphuric acid by contact process.

Question 26:
Differentiate ferrimagnetism from paramagnetism and predicts the change that takes place to ferrimagnetic substances on heating.

Question 27:
a. Draw the structure of dichromate ion.
b. How can dichromate ion be converted to chromate ion?
c. Write examples for the oxidising action of potassium dichromate in acidic medium.

Question 28:
Explain the following
a. Hydraulic washings
b. zone refining
c. Roasting of ores

Question 29:
Describe the following reactions.
a. Aldol condensation
b. Etard reaction
c. Rosenmund reduction

Questions from 30 to 33 carry 4 score. Answer any 3 questions.

Question 30:
Write chemical equations for the conversion of phenol to acetyl salicylic acid (aspirin)

Question 31:
With the help of diagram describe the construction and working of a fuel cell using H₂, and O₂. What are the advantages of fuel cell over conventional cells.

Question 32:
Sketch the Crystal field splittng of d-orbit- als of the Central metal ion in [CoF₆]^3-. Also write the electronic configuration of central metal ion and predict its magnetic behaviour based on crystal field theory.

Question 33:
Give the structure and IUPAC names of the products formed on the following reactions
a. Hydration of propene in the presence of dilute sulphuric acid.
b. Reaction of methanal with methyl mag-nesium bromide followed by hydrolysis.

Answers

Answer 1:
Cubic

Answer 2:
Teflon

Answer 3:
Cr²⁺(4 unpaired d electrons)

Answer 4:
Order of the reaction = \(\frac { 1 }{ 2 }\) + \(\frac { 3 }{ 2 }\) = \(\frac { 4 }{ 2 }\) = 2

Answer 5:
iv

Answer 6:
Glycogen

Answer 7:
Tranquilizers

Answer 8:

Answer 9:
In bcc

Answer 10:
Sulphur dioxide is formed together with a little (6 – 8%) sulphur trioxide when sul¬phur is burnt in air or oxygen.

S(s) + O₂(g) → SO₂(g)

SO₂ is a colourless and pungent smell gas It can detected by using potassium permag- nate solution when SO₂ is passed through an acidified potassium permanganate solu¬tion, then it decolonises the solution as it reduces MnO₄^– ions to Mn²⁺ ions. SO₂ give out suffocating smell which indicates its presence

Answer 11:
a. Potassium hexacyanoferrate (III).
b. Dichloridobis (ethane -1,2- diamine) cobalt (III) chloride.

Answer 12:
Vant Hoff factor is the ratio of the observed college five property to the normal colligative property
i = \(\frac { observed collegative property }{ Theoretical collegative property }\)
Dilute solution of K₂SO₄( would dissociate into two K⁺ ions and a sulphate ion.
K₂SO₄ → 2K⁺ + SO₄^2-
The Van’t hoff factor for a dilute solution of K₂SO₄ is 3.

Answer 13:

Answer 14:
Cannizzaro reaction which do not have an a-hydrogen atom, undergo self oxidation and reduction (disproportionation) reaction on heating with concetrated alkali. In this reaction, one molecule of the aldehyde is reduced to alcohol while another is oxidised to carboxylic acid salt.

Answer 15:

Answer 16:
Hydrolysis of sucrose gives equimolar mixture of D – (+) – glucose and D – (-) fractose.

Sucrose ¡s non-reducing sugar because aldehyde group of glucose and keto group of fractose are not fuce and involved in glycosidic bond formation.

Answer 17:
The reaction between tert-butyl bromide and hydroxide ion yields tert-butyl alcohol and follows the first of order kinetics, i.e, the rate of reaction depends upon the concetration of only one reactant, which is tert butyl bromide.
(CH₃)₃ CBr + NaOH → (CH₃)₃COH + NaBr
If occurs in two steps
Step I : The polarised C-Br bond under¬goes slow clearage to produce a carbocation and a bromide ion. The carbocation thus formed is then attacked by nucleophile in step II to complete the substitution reaction.

Answer 18:

Answer 19:
a. Antiseptic                                  –            bithional
b. Artificial sweetners                 –            Saccharin
c. Soap                                            –            Sodium stearate
d. Vitamin C                                  –           ascorbic acid

Answer 20:
Ethanal give silver mirror with tollens reagent where as propanone will not react

Answer 21:

Answer 22:
There are 3 allotropic forms of phosphorus.

White phosphrous:

• Translucent white waxy solid
•  Garlic smell
• Poisonous
•  Less stable due to angle strain. (60° PPP bond angle)
• Readily catches fire in air.
  

Red phosphorus:

• Iron grey lustrous powder
• Odourless
• Non-poisonous
•  More stable than white phosphorus
  

Black phosphorus:
It has two forms α black phosphorus and β black phosphorus. When white phosphorus is heated under high pressure at 473 K β black phosphorus is formed.

Answer 23:

Answer 24:
The relationship between extent of adsorption and pressure of the gas at constant temperature is called adsorption isotherm and is given by
\(\frac { x }{ m }\) = kp ^{\(\frac { 1 }{ n }\)} (n> 1)
Freundlich Adsorption Isotherm
where x = mass of gas adsorbed on ‘m’ mass of the adsorbent at p pressure, k, n are constants.

Observations:

• At low pressure \(\frac { x }{ m }\) ∝ p (graph is linear).
•  At high pressure \(\frac { x }{ m }\) is independent of p (graph – straight line).
• At intermediate pressure \(\frac { x }{ m }\) = kp^{\(\frac { 1 }{ n }\)}

Taking logarithm on both sides. We get

In case of a solution, the isotherm takes the form, x = k(C)^{\(\frac { 1 }{ n }\)}

Answer 25:
H₂SO₄ is manufactural by the contact process which involves three steps
(1) Burning of sulphur or sulphide uses in air to generate SO₂
S + O₂ → SO₂

(2) Conversion of SO₂ to SO₃ by the reaction with oxygen in the presence of a catalyst
2SO₂(g) + O₂(g) \(\underrightarrow { { V }_{ 2 }{ O }_{ 5 } }\) 2SO₃(g)
Absorption of SO₃in H₂SO₄ to give oleum (H₂S₂O₇)
SO₃ + H₂SO₄(dil) → H₂S₂O₇ (Oleum)
Oleum is diluted with water to form H2S04
H₂S₂O₇+ H₂O → 2H₂SO₄

Answer 26:
Ferrimagnetism is observed when the magnetic moments of the domains in the sub-stances are aligned in parallel and antiparallel directions in unusual numbers. They are weakly attracted by magnetic field as compared to ferromagnetic substances.
Paramagnetic substances are weakly attracted by a magnetic field. They are magnetised in a magnetic field in the same direction. They lose their magnetism in they absence of magnetic field. Paramagnetism is due to presence of one or more unpaired electrone which are attracted by the magnetic field.
Ferrimagnetic substance lose ferrimagnetism on heating and become paramagnetic.

Answer 27:

b. The chromate and dichromateions are interconvertible in aqueous solution depending upon the pH of the solution

Acidified potassium dichromate will oxidise iodides to iodine sulphides to sulphur.
tin (II) to tin (iv) and iron (ii) salt to iron (iii)

Answer 28:
a. It is also called gravity separation. It is based on the difference in densities (gravities) of ore and the gangue. Ore is washed with stream of water so that light impurities are washed away, eg., haematite.
b. It is based on the principle that the im-purities are more soluble in the melt than in the solid state of metal.

The impure metal is heated with the help of a circular mobile heater at one end. This results in the formation of a molten zone. As the heater is moved along the rod, pure metal crystallises out of the melt and impurities pass onto the adjacent molten zone. This is reimpurities at one end of the rod is cut off and discarded.

•  Metals like Si, Ge, Ga, B etc are refined by this method (semi-conductors and metals of high purity).

c. It is a process in which an ore is heated in regular supply of air at a temperature below the melting point of the metal so as to convert the give ore into oxide ore.
2ZnS + 3O₂ → 2ZnO + 2SO₂

Answer 29:
a. Aldehydes and ketones having at least one α hydrogen undergo a reaction in the presence of dilute alkali as catalyst to form β – hydroxy aldehydes (aldol) or β hydroxy ketones (ketol), respectively. This is known as aldol reaction. The aldol and ketol readily lose water to give α, β – unsaturated carbonyl compounds which are aldol condensation products and the reaction is called aldol condensation

b. Strong oxidising agents oxidise tolerene and derivatives to benzoic acids. How-ever, it is possible to stop the oxidation at the aldehyde stage with suitable reagents that convert the muthyl group to an inter¬mediate. Chromy chloride (CrO₂Cl₂) oxidise methyl group to a chromium complex, which on hydrolysis gives corresponding benzaldehyde.

This reaction is called Etard reaction

c. Acyl chloride (acid chloride) is hydrogenated over catalyst, palladium on burium sulphate. This reaction is called Rosenmund reduction.

Answer 30:
Kolbe’s reaction : Phenoxide ion generated by treating phenol with sodium hydroxide is even more reactive than phenol towards electrophilic aromatic substitution. Hence if undergoes electrophilic substitution with CO₂, a weak electrophite. Ortho hydroxybenzoic acid is formed as the main reaction product.

Answer 31:
Fuel Cells: They produce electrical energy directly from the combustion of fuels such as hydrogen. carbon monoxide or methane. It is a Galvanic cell.

The electrode reactions of the most popular fuel cell H₂– O₂ cell is given below:

Advantages:

• PoHution-free.
•  High efficiency (70%).
• Continuous source of energy if gas supply ‘s maintained.
•  The electrodes used in fuel cells are not affected during its working.

Answer 32:
[C0F₆]³Here cobalt is in the +3 oxidation state.

But F^– is a weak ligand. So pairing does not take place. Hence in metal ion under goes sp³d² hybridisation. There are four unpaired electrons present, therefore the complex is paramagnetic.

Answer 33:
a. When hydration of propene in the presence of dilute sulphuric acid. If gives


The grignard reagents (R-Mg -X) react with compounds containing \(\begin{matrix} | \\ C \\ | \end{matrix}\) = o to form addition compounds, which on hydrolysis with dil acid give the corresponding alcohols.Methanal react with grignai reagent to give a primary alcohol.

Plus Two Chemistry Previous Year Question Papers and Answers

Kerala Plus Two Chemistry Model Question Paper 4

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 of 2 hrs.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• Read the instructions carefully.
• 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 one score each. Answer all questions.

Question 1.
Saline water is a solution.

a. Isotonic
b. Hypertonic
c. Hypotonic
d. Heavy water

Question 2.
Name the law which states that partial pressure of a gas is directly proportional to its mole fraction.

Question 3.
A crystalline solid

a. changes abruptly from solid to liquid
b. has no definite melting point
c. Undergoes deforestation of its geometry easily
d. has an irregular 3dimensional arrangement.

Question 4.
Galvanization of iron denotes coating with

a. Al
b. Sn
c. Cd
d. Zn

Question 5.
Write an example of an emulsion.

Question 6.
The formation of micelles takes place on above

a. Inversion temperature
b. Boyle temperature
c. Critical temperature
d. Kraft temperature

Question 7.
Complete the reaction.

(Questions 8 to 20) : Answer any ten. Each questions carries two scores.

Question 8.
Vapour pressure of a solution is different from that of the pure solvent.
i. Name the law which helps us to determine partial vapour pressure of a volatile component in solution.
ii. State the above law?

Question 9.
Zero-order reaction means that the rate of a reaction is independent of the concentration of reactants.
i. Write an example of a zero order reaction.
ii. Write the integral rate expression for the zero order reaction, R → P

Question 10.
a. How will you distinguish primary and secondary alcohols using Luca’s test?
b. Write the correct pair of reactants for the preparation of butyl ethyl ether by Williamson synthesis.

Question 11.
Two chemical reactions are given below:
1. Identify the products of each reaction.
2. Give the name of each reaction.

Question 12.
200 cm³ of an aqueous solution of a protein contains 1.26 g of protein. The osmotic pressure of a solution of 300 K is found to be 8.3 × 10^-2 bar. Calculate the molar mass of protein. (R= 0.083 L bar K^-1 mol^-1)

Question 13.
i. The number of moles of the solute per kilogram of the solvent is
a. Mole fraction
b. Molality
c. Molarity
d. Molar mass
ii. ‘The extent to which a solute is dissociated or associated can be expressed by Can’t Hoff factor.’ Substantiate the statement.

Question 14.
Presence of excess sodium makes NaCl crystal coloured. Explain on the basis of crystal defects.

Question 15.
Explain the following:
i. Esterification
ii. Williamson Synthesis

Question 16.
Aldehydes, Ketones and Acids contain

a. Name the product obtained by the reaction between Acetic acid and Ethanol.
b. Give any two tests to distinguish between aldehydes and ketones.

Question 17.
a. Among the following which is not a colligative property?
i. Osmotic pressure
ii. Bevation of boiling point
iii. Vapour pressure
iv. Depression of freezing point
b. What is the significance of Can’t Hoff factor?

Question 18.
One of the fuel cells uses the reaction of hydrogen and oxygen to form water. Write down the cell reaction taking place in the anode and cathode of that fuel cell.

Question 19.
The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatile, nonelectrolyte solid weighing 0.5g when added to 39 g of benzene (molar mass 78 g/mol), vapour pressure becomes 0.845 bar. What is the molar mass of the solid substance?

Question 20.
a. Write down the ionization isomer of [CO(NH₃)₅Cl] SO₄
b. Write the IUPAC name of the above compound.

(Questions 21 to 29): Answer any seven. Each question carries three scores.

Question 21.
i. Which of the following oxidation state is ! not shown by Manganese?
a. + 1
b. +2
c. +4
d. +7
ii. Represent the structure of dichromate ion.
iii. Potassium permanganate (KMnO₄) is a strong oxidizing agent. Write any two oxidizing reactions of KMnO₄.

Question 22.
Account for the following:
i. H₂O is a liquid while H2S is a gas.
ii. Noble gases have very low boiling points.
iii. NO₂ dimerises to N₂O₄.

Question 23.
How will you bring below the following conversions? (Write the chemical equations)
i. Ethanol → Ethanoic acid
ii. Benzamide → benzoic acid
iii. Benzaldehyde → meta nitro benzaldehyde

Question 24.
Amines are classified as primary, secondary and tertiary.
a. Write the IUPAC name of the following compound: NH₂-(CH₂)₆ NH₂
b. Which is stronger base CH₃NH₂ or C₆H₅NH₂? Why?

Question 25.
a. Which named reaction is used to reduce CH₃COCl to CH₃CHO?
b. Aldehydes and Ketones undergo reactions due to the presence of hydrogen I atom.
i. Write the name of the reaction of aldehydes which take place only because of the presence of a hydrogen atom.
ii. How will you bring about the above reaction?

Question 26.
Amines are classified as a primary, secondary and tertiary amine.
a. How will you convert nitrobenzene to aniline?
b. Represent the structure of secondary and tertiary amine.
c. Aniline does not undergo Friedel Craft’s reaction. Why?

Question 27.
Nucleophilic substitution reactions are of two types of SN reactions and SN reactions,
a. Write any 2 differences between \({ S }_{ N }^{ 1 }\) and \({ S }_{ N }^{ 2 }\) reactions.
b. Write any 2 reasons for the less reactivity of aryl halides towards nucleophilic substitution reactions.

Question 28.
Primary, secondary and tertiary amines can be distinguished using Hinsberg’s reagent.
i. What is Hinsberg’s reagent?
ii. How will you distinguish primary, secondary and tertiary amines using Hinsberg’s reagent?

Question 29.
Schottky defects and Frenkel defects are two stoichiometric defects shown by crystals.
i. Classify the following crystals into those showing Schottky defects and Frenkel defects: NaCl, AgCl, CsCl, CdCl₂
ii. Name a crystal showing both Schottky defect and Frenkel defect.

(Questions 30 to 33): Answer any three. Each question carries four scores.

Question 30.
a. Account for the following:
i. NH₃ acts as a Lewis base.
ii. PCl₃ fumes in moist air.
b.
i. Suggest any two fluorides of Xenon.
ii. Write a method to prepare any one of the above-mentioned Xenon fluorides.

Question 31.
Some elements in block show allotropy.
a. What are the allotropic forms of sulphur?
b.
i. How will you manufacture sulphuric acid by contact process?
ii. What is an interhalogen compound?

Question 32.
Potassium dichromate is an orange coloured crystal and is an important compound used as an oxidant in many reactions.
a. How do you prepare K₂Cr₂O₇ from chromite ore?
b. How will you account for the colour of ! potassium dichromate crystals?

Question 33.
a. Most important chemical reactions of haloalkanes are their substitution reactions.
i. What is \({ S }_{ N }^{ 1 }\) reaction?
ii. Arrange the four isomeric Bromo butanes in the increasing order of their reactivity towards SN1 reaction.
b. How will you prepare chlorobenzene from benzene diazonium chloride?

Answers

Answer 1.
hypertonic

Answer 2.
Henry’s law

Answer 3.
a

Answer 4.
d

Answer 5.
MIlk

Answer 6.
d

Answer 7.
Bakelite

Answer 8.
i. Raoult’s law.
ii. For a solution of volatile liquids, the partial vapour pressure of each component ¡n the solution is directly proportional to its mole fraction of component in the solution.

Answer 9.
i. Decomposition of ammonia gas on a hot platinum surface.
ii. K = [R₀]-[R]; where R₀ is the initial concentration of the reactants, R is the concentration at a time and K is the rate constant.

Answer 10.
a. Alcohols are soluble in Lucas reagent and their halides are immiscible and form turbidity 3° alcohols produce turbidity immediately 2° alcohols produce turbidity within a few minutes whereas 1° alcohol does not produce turbidity at all at room temperature.

Answer 11.

2. Clemmensen reduction, Gattermann Koch reaction.

Answer 12.

Answer 13.
i. b. Molality
ii. In the case of dissociation, the observed molecular weight has a lower value than the normal molecular weight while in the case of an association, the observed molecular weight is higher than the normal molecular weight. In order to explain such j abnormal cases, Can’t Hoff factor is used. This factor is defined as

Answer 14.
Presence of excess sodium makes NaCl crystal coloured, this is caused by metal excess defect due to anionic vacancies. When NaCl crystal is heated in an atmosphere of sodium vapour, the sodium j atoms are deposited on the surface of the crystal and combine with Na atoms to give NaCl. The released electrons diffuse into the crystal and occupy an anionic site. As a result of the crystal now has an excess of sodium. The anionic sites occupied unpaired electrons are F centres. They impart a yellow colour to the crystals of NaCl.

Answer 15.
i. Alcohols and phenols react with carboxylic acids, acid chlorides and acid anhydrides to form esters.

ii. It is an important laboratory method for the preparation of symmetrical and unsymmetrical ethers. In this method, an alkyl halide is allowed to react with sodium alkoxide.

Answer 16.
a. Acetic acid and ethanol react in the presence of H₂SO₄/H₂O to form ethyl acetate. This is called esterification.

b. Aldehydes answer Tollen’s test. On warming an aldehyde with Tollen’s reagent, a bright silver mirror is produced due to the formation of silver metal. Ketones do not answer this test, in presence of HCl.

Fehling’s test: Aldehydes on heating with Fehling’s solution give a reddish brown precipitate. Ketones do not answer this.

Answer 17.
a. Vapour pressure.
b. In the case of dissociation, the observed molecular weight has a lower value than the normal molecular weight while in the case of an association, the observed molecular weight is higher than the normal molecular weight. In order to explain such abnormal cases, Can’t Hoff factor is used.

Answer 18.
The electrode reactions are:

Answer 19.

Answer 20.
a. [Co(NH₃)₅SO₄]Cl
b. Pentaamminesulphatocobalt (II) chloride

Answer 21.

Answer 22.
i. Due to the presence of H-bonding in between H₂O molecule they exist as a liquid. But no such H bonding is there In H₂S due to less electronegative nature and large size compared to oxygen.
ii. Noble gases being monoatomic have no interatomic forces except weak dispersion forces and therefore, they are liquefied at very low temperatures. Hence, they have low melting points.
iii. NO₂ contains an odd number of valence electrons. It behaves as a typical odd molecule. On dimerisation, it is converted to stable N.O. molecule with an even number of electrons.

Answer 23.

Answer 24.
a. Hexane 1,6 diamine.
b. The stronger base is CH₃NH₂. Presence of + 1 group (CH₃) increases the electron density on Natom and thus basicity increases.

Answer 25.
a. Rosenmund reduction.
b.
i. Aldol condensation.
ii. Aldehydes and ketones having at least one a hydrogen atom in presence of dilute alkali given hydroxy aldehydes.

Answer 26.


c. The catalyst in FriedalCraft’s reaction is any. AlCl₃, it, is a Lewis acid so get coordinated with electron pair of N atom in aniline. So an electrophile cannot attack the ring.

Answer 27.
a.

b.
1) Aryl halides are electron rich.
2) In aryl halides, the halogen is attached to an sp2 hybridised C, which is highly stable.

Answer 28.
i. Benzene sulphonyl chloride.
ii. 1° amine react with Flinsberg’s reagent to form sulphonamides which is soluble in alkali. 2° amines react with Hinsberg’s reagent forming sulphonamides insoluble in alkali. 3° amines do not react with Flinsberg’s reagent.

Answer 29.
i. Schottky defect : NaCl, CsCl Frenkel defect: AgCl, CdCl₂
ii. AgBr.

Answer 30.
a. i. The nitrogen atom in NFH₃ has one lone pair of electrons which is available for donation. So it acts as a Lewis base,
ii. PCl₃ undergo hydrolysis in presence of moisture giving fumes of HCl.

b.

Answer 31.
a. Rhombic sulphur or sulphur and monoclinic sulphur or p sulphur,
b.
i. Contact process.
Burning of sulphur in the air to generate SO₂. Conversion of SO₂ to SO₃ by there action with oxygen in the presence of a catalyst (V₂O₅).
Absorption of SO₃ in H₂S0₄ to give Oleum. Oleum with water gives H₂SO₄.
ii. Halogens can react themselves to form binary compounds known as interhalogen compounds. They are more reactive than halogens because in the difference in electronegativity of the combining halogens.

Answer 32.
a. K₂Cr₂ O₇ is prepared from chromite ore by heating with Na₂CO₃ in the presence of air when sodium chromate is formed.

The soluble Na₂CrO₄ on acidification with H₂SO₄ produces sodium dichromate which on treating with KCl gives potassium dichromate.

b. Coloured property of potassium dichromate is due to the presence of unpair electron when light falls on the compound the unpair electron undergoes dd electron transmission. This creates the colour for the potassium dichromate.

Answer 33.
a. i. First, the carbocation is formed (slow, rate determining) and then nucleophile attacks (fast). Order of reactivity of alkyl halides is 3°> 2° > 1 “(due to decreasing stability of carbocation). It results in racemization. ie., retention as well as inversion.

Plus Two Chemistry Previous Year Question Papers and Answers

Kerala Plus Two Chemistry 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 of 2 hrs.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• Read the instructions carefully.
• 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 one score each. Answer all questions.

Question 1.
The polymer used in orthopaedic devices j and in controlled drug release is

Question 2.
Which one among the following is not an analgesic?

a. Ibuprofen
b. Naproxen
c. Aspirin
d. Valium

Question 3.
Addition of Grignard reagent to an aldehyde j or ketone gives an ;

a. anomer
b. ether
c. ester
d. alcohol

Question 4.
Following graph is a plot of the rate of a reaction vs concentration of the reactant, What is the order of the reaction?

Question 5.
How will the pH of brine ( aq. NaCl solution) effect when it is electrolysis?

Question 6.
Which stoichiometric defect in crystal increased the density of a solid?

Question 7.
Given an example of a material used for making semipermeable membrane for carrying out reverse osmosis.

(Questions 8 to 20) : Answer any ten. Each questions carries two scores.

Question 8.
a. Identify an analgesic from the following:
i. Equanil
ii. aspirin
iii. serotonin
iv. cimetidine
b. Differentiate between antiseptics and antibiotics.

Question 9.
a. Among the following which one is chlorine containing insecticide?
(i) DDT
(ii) Freon
(iii) Phosgene
(iv) Iodoform
b. Haloarenes undergo WurtzFitting reaction. What is WurtzFitting reaction?

Question 10.

Write the formulae of A and B in the above reaction.

Question 11.
Every substance has some magnetic properties associated with it. How will you account for the following magnetic properties?
i. Paramagnetic property
ii. Ferromagnetic property

Question 12.
Osmotic pressure is a colligative property and it is proportional to the molarity of the solution.
a. What is osmotic pressure?
b. The molecular mass of NaCI determined by osmotic pressure measurement is found to be half of the actual value. Account for it.

Question 13.
Aldol condensation reaction is a special reaction of aldehydes.
i. What is aldol condensation reaction?
ii. Write the structural formula of aldol formed from ethanol.

Question 14.
Synthetic rubber is a Vulcanisable rubber-like polymer.
i. Wite one example for synthetic rubber.
ii. Write the method of preparation of the above synthetic rubber.

Question 15.
A compound is formed by two elements P and Q. Atoms of Q (as anions) make hep lattice and those of the element P (as cations) occupy all the tetrahedral voids. What is the formula of the compound?

Question 16.
Write simple chemical tests and observations used to distinguish between the following compounds.
i. Propanal and propanone
ii. Phenol and benzoic acid

Question 17.
Calculate the osmotic pressure exerted to a solution prepared by dissolving 1.5 g of a polymer of molar mass 185000 in 500 ml of water at 37°C. [R = 0.0821 L atm K^-1 mol^-1]

Question 18.
Colligative properties can be used to determine the molecular mass of solutes in solutions.
a. What do you mean by coffigative property’?
b. For determining the molecular mass of polymers, osmotic pressure is preferred to other properties. Why?

Question 19.
The limiting molar conductivity of an electrolyte is obtained by adding the limiting molar conductivities of cation and anion of the electrolyte.
a. Name the above law.
b. What is meant by limiting molar conductivity?

Question 20.
Which are the monomers of Nylon6 and Nylon66?

(Questions 21 to 29): Answer any seven. Each questions carries three scores.

Question 21.
a. Explain how conductivity measurements help to determine the ionisation con start a weak electrolyte like acetic acid.
b. Explain the change of conductivity and molar conductivity of a solution with dilution?

Question 22.
a. Atomic sizes increase as we come down
a group, but in 4^th group of the periodic table Zr, Hf has almost the same atomic sizes. Why?
b. E° (Standard electrode potential) values generally become less negative as we move across a transition series, but E° values of Ni²⁺/Ni and Zn²⁺/Zn values are exceptions.

Question 23.
Phenols are more acidic than alcohols.
a. Name the product obtained when phenol is treated with chloroform in presence of NaOH.
b. Name the above reaction.
c. What is the product obtained when phenol is treated with conc.HNO₃?

Question 24.
a. Amines are versatile functional group useful in the preparation of many organic compounds. How can you convert?

b. A student tried to prepare nitro aniline by nitrating aniline with a cone. HNO₃ cone. H₂SO₄ mixture, but he got only m nitroaniline. Why?
c. Explain how to prepare nitro aniline from aniline?

Question 25.
Colloids exhibit certain special properties,
a. Name the property of colloid involved in j the construction of ultramicroscope?
b. Explain the above property.
c. What are the conditions to be satisfied to exhibit Tyndall effect?

Question 26.
Aromatic amines are important synthetic intermediates.
i. What are the products obtained when aniline is treated with Bromine water?
ii. How will you convert nitrobenzene to aniline?
iii. Write down the isocyanide test for the primary amines.

Question 27.
Carbohydrates can be divided into three major classes monosaccharides, oligosaccharides and polysaccharides.
a. What are polysaccharides?
b. Give two examples for polysaccharides.
c. What is invert sugar?

Question 28.
Antibiotics, antiseptics and disinfectants are antimicrobial drugs.
a. Give 2 examples of antibiotics.
b. Write one similarity between antiseptics and disinfectants.
c. Write one difference between antiseptics and disinfectants.

Question 29.
[Cr(NH₃)₄CI₂]Br is a coordination compound.
a. Identify the central metal ion of the above compound.
b. Name the ligands present in it.
c. What is the coordination number?

(Questions 30 to 33): Answer any three. Each questions carries four scores

Question 30.
Colligative properties are properties of solutions which depend on the number of solute particles irrespective of their nature.
a. Name the four important colligative properties.
b. What happens to the colligative properties when ethanoic acid is treated with benzene? Give reason.

Question 31.
The order of a chemical reaction can be zero and even a fraction, but molecularity cannot be zero or a non-integer.
i. What do you mean by the order of a reaction?
ii. What is molecularity of a reaction?
iii. The conversion of molecules ‘A’ to‘B’ follows second order kinetics. If concern traction of ‘A’ is increased to three times, how will it affect the rate of formation of ‘B’?

Question 32.
The geometry and magnetic properties of complexes can be explained by VB Theory. The octahedral complex [CO(NH₃)₆]³⁺ is diamagnetic, while the octahedral complex [COF₆]^3-is paramagnetic. Explain using VB theory?

Question 33.

a. What is its IUPAC name?
b. Explain the conversion of the above acid into the following.

Answers

Answer 1.
d

Answer 2.
Valium

Answer 3.
d

Answer 4.
Zero-order reaction

Answer 5.
It will increase due to the formation of NaOH.

Answer 6.
Interstitial defect

Answer 7.
Cellulose acetate

Answer 8.
a. ii. aspirin
b. Antiseptics are substances which prevent the growth of microorganisms or kill them but are not harmful to the living human tissues. Antibiotics are drugs used to treat infections in our body. it inhibits the growth of microorganisms.

Answer 9.
a. ii.DDT
b. When aryl halide is heated with an alkyl halide in the presence of sodium in dry ether, a halogen atom is replaced by an alkyl group and alkylarene is formed. This process is called Wurtz Fitting reaction.

Answer 10.

Answer 11.
i. Paramagnetic property is the property formed by the substance as it is early attracted by the magnetic field m.field). Magnetic alignments are in same direction, eg., O₂, Fe³⁺.
ii. ferromagnetic property is the property formed by the substance due to strongly attracted by the magnetic field. Magnetic alignments are in same direction, eg., CO, Ni.

Answer 12.
a. osmotic pressure is the external pressure squired to stop the flow of solvent mole ule from higher concentration to lower concentration through a semipermeable membrane. It is a colligative property.
b. dilution no. of molecules increases, therefore mass decreases. On dilution, laCI dissociates to two molecules? So a solar mass decreases to half.

Answer 13.
i. Idol condensation reaction. dehyde and Ketones having one hydrogen react in the presence of dilute skill to form aldol and Ketol, which no further reaction and release water molecule to form α, β unsaturated compound.

Answer 14.
i. Neoprene.
ii. By the polymerisation of chlorine

Answer 15.
No. of atoms of Q = N No. of atoms of P = 2N
∴ The ratio of atoms of P & Q = 21
∴ The formula = P₂Q

Answer 16.
i. Tollen’s test
ii. Iodoform test

Answer 17.

Answer 18.
a. Properties which depend on the number of particles and not on it nature are called colligative property
b. This is because in the osmotic pressure method, the pressure is measured at room temperature and molarity the solution is used instead of mole

Answer 19.
a. Kohlrausch’s law.
b. It is the molar conductivity of electrolytes at zero concentration or at infinite dilution.

Answer 20.
Nylon-6 Caprolactam
Nylon-66 Hexamethylenediamine and adipic acid

Answer 21.
a. The degree of dissociation can be determined by the equation, α = \(\frac { { \lambda }_{ m } }{ { \lambda }_{ 0 }^{ m } }\) To obtain ionisation constant, K_a, sub stitute a in the following equation, \({ K }_{ a }=\frac { { Ca }^{ 2 } }{ \left( 1-\alpha \right) }\) ;where C is the concentration a of acetic acid in moles/litre.
b. Conductivity of a solution decreases with a decrease in concentration as the number of ions present per unit volume of the solution actually decreases. The molar conductivity of electrolytes increases with a decrease in concentration.

Answer 22.
a. Due to lanthanoid contraction, size of 2nd series Zr and 3^rd series Hf elements are almost similar.
b. The exceptional behaviour of Ni is due to its high negative enthalpy of hydration. Since Zn has completely filled orbitals, it E? value is more negative than expected.

Answer 23.
a. Salicylaldehyde.
b. Reimer-Tiemann reaction.
c. Picric acid is formed.

Answer 24.

b. Due to the formation of anilinium ion, since -N⁺H₃ is a meta directing group, meta nitro aniline is obtained.
c. NH₂ group is protected from protonation by acetylation.

Answer 25.
a. Tyndall effect.
b. The phenomenon of scattering of light by colloidal particles when a beam of light is passed through it is called the Tyndall effect.
c.
i. The size of the colloidal particles and the wavelength of the light used sho could be comparable.
ii. There should be a very large difference between the dispersed phase arid I dispersion medium.

Answer 26.

iii. Carbylamine reaction.
1° amine on heating with chloroform j and ethanolic KOH form isocyanides.

Answer 27.
a. Polysaccharides give a large number of monosaccharide units on hydrolysis.
b. Starch and cellulose.
c. Sucrose solution is dextrorotatory. When it is subjected to hydrolysis, the resultant sugar-solution becomes levorotatory. This sugar is called invert sugar.

Answer 28.
a. Penicillin, ofloxacin.
b. Antiseptics and disinfectants are chemicals which prevent or kill the growth of microorganisms.
c. Antiseptics are applied to living tissues such as wounds, cuts, ulcers etc to kill microorganisms. Disinfectants are applied on floors, drainage system like nonliving materials to kill microorganisms.

Answer 29.
a. Chromium.
b. Ammonia, Chloride,
c. 6

Answer 30.
a.
1. Lowering of vapour pressure
2. The salvation of boiling point
3. Depression in freezing point
4. Osmotic pressure.
b. Due to an association of molecules, the ‘ number of particle decreases and colligative property decreases. Molecules of ethanoic acid dimerise in benzene due to hydrogen bonding.

Answer 31.
i. Order of a reaction is the sum of the powers of the concentration terms of the reactants as expressed in the rate equation.
ii. It is the no. of molecules of the reactants that collide simultaneously to bring about the chemical reaction.
iii. r = K. [A]²
r, = K. [3A]² = 9. K [A]²
∴ Rate increases by 9 times.

Answer 32.
The outer electronic configuration of cobalt is 3d⁷ 4s². In this complex, cobalt is in the +3 oxidation state. So electronic configuration of CO³⁺ is 3d⁶ 4s° is

Ammonia is a strong ligand. Therefore pairing of electrons takes place,

There are six ammonia molecules acting as ligands. So there should be six vacant orbitals for Co³⁺. Hence the metal ion undergoes d2sp3 hybridisation. Since there are no unpaired electrons, the complex is diamagnetic. [COF₆]^3- Here also cobalt is in the +3 oxidation state.

But P is a weak ligand. So pairing does not take place. Hence in metal ion undergoes sp³d² hybridisation. There are four unpaired electrons present, .. the complex is paramagnetic.

Answer 33.
a. 3,4dinitrobenzoic acid,

Plus Two Chemistry Previous Year Question Papers and Answers

Kerala Plus Two Chemistry 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 of 2 hrs.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• Read the instructions carefully.
• 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 one score each. Answer all questions.

Question 1.
Which type of stoichiometric defect am I shown by AgCI?

Question 2.
What is the two-dimensional coordination; a number of a molecule in a square close-packed later?

Question 3.
Mercury is a ……… cell.

Question 4.
For the reaction ; Cl₂ (g) + 2NO(g) → 2NOCI(g) ; the rate law is expressed as rate = K[CI₂][NO]² ! What is the overall order of this reaction?

Question 5.
Name the method used for removing gangue I from sulfide ore.

Question 6.
Which one of the following compound reacts, with chlorobenzene to produce DDT?

Question 7.
Biotin is an organic compound present in yeast deficiency in the diet causes dermatitis 1 and paralysis. It is also known as

a. Vitamin H
b. Vitamin B₃
c. Vitamin B₁₂
d. VitaminD

(Questions 8 to 20) : Answer any ten. Each question carries two scores.

Question 8.
i. Which of the following is a molecular solid?
a. Diamond
b. Graphite
c. Ice
d. Quartz
ii. Unit cells can be classified into primitive and centered unit cells. Differentiate between primitive and centered unit cells

Question 9.
i. Which of the following is a secondary cell?
a. Dry cell
b. Leclanche cell
c. Mercury cell
d. None of these
ii. What is the relationship between resistance and conductance?

Question 10.
Complete the following.

Question 11.
Match the items of Column I with items of Column II.


Question 12.
How will you convert propanoic acid into the following compounds?
i. Ethane 0
ii. Butane

Question 13.
Haloalkanes and haloarenes react with metals to give hydrocarbons or products from which hydrocarbons are obtained easily.

Identify the product and name the reaction.

Identify the product and name the reaction.

Question 14.
Most of the organic chlorides, bromides and iodides react with certain metals to give compounds containing carbon-metal bonds.
i. Give one example of such a compound.
ii. How will you prepare the above compound?

Question 15.
Schematic alignment of magnetic moments of ferromagnetic, antiferromagnetic and ferrimagnetic substances are given below. Identify each of them.

Question 16.
Aldehydes and ketones are organic compounds containing a carbonyl group.
i. Write a chemical reaction to distinguish between aldehydes and ketones.
ii. Aldehydes and ketones can be subjected to Clemmensen reduction and wolfishness reduction. Name the reagents used in both cases.

Question 17.
Write any two electrophilic substitution reactions of chlorobenzene.

Question 18.
a. Which of the ones mentioned in the above table can be concentrated by magnetic separation. justify your answer.
b. Identify the ones that can be concentrated by leaching.

Question 19.
The temperature dependence of the rate of a chemical reaction can be accurately explained by Arrhenius equation. With the help of the Arrhenius equation calculate the rate constant for the first order reaction, C₂ H₅ I_(g) → C₂ H_4(g) + HI_(g) at 700 K. Energy of activation (E_a) for the reaction is 209 KJmof1 and rate constant at 600 K is 1.60 x 105 S’1. [Universal gas constant R= 8.314K1mol’1].

Question 20.
Chemotherapy is a term found in medical terminology. What is chemotherapy?

(Questions 21 to 29): Answer any seven. Each questions carries three scores.

Question 21.
a. The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is termed adsorption.
i. What is adsorption isotherm?
ii. Write the mathematical expression of Freundlich adsorption isotherm.
b. Enzymes are known as biochemical catalysts. Write any two important characteristics of enzyme catalysis.

Question 22.
Biomolecules are formed by certain specific linkages between simple monomeric units. Write the names of linkages and monomeric units in the following class of biomolecules.
i. Starch
ii. Protein
iii. Nucleic acid

Question 23.
Polymers are macromolecules formed by a union of monomers.
a. Name natural polymer and synthetic polymer.
b. Distinguish between thermoplastic and thermosetting polymers with an example.

Question 24.
Carbohydrates are broadly divided into monosaccharides, oligosaccharides, and polysaccharides.
a. Write one example each of monosaccharide and oligosaccharide.
b. i. Write any one method for the preparation of glucose.
ii. What is peptide linkage?

Question 25.
a. Amines are basic in nature. Arrange the following compounds in the increasing order of their basic strength.
NH₂, C₆H₅NH₂, CH₃ NH₂, (CH₃) 2NH, (CH₃)₃N.
b. How will you convert Toluene (C₆H₅CH₃) to Benzaldehyde

Question 26.
Consider the coordination compound [CO(NH₃)₅ SO₄]Br.
a. Write the IUPAC name of the above compound.
b. What is the primary valence and secondary valence of the central metal, Cobalt, in the above coordination compound?
c. Which type of structural isomerism is exhibited by the above coordination compound?

Question 27.
Different drugs have different therapeutic action in our body. Write the therapeutic action of the following drugs in our body.
a. Tranquilizers
b. Analgesics
c. Antibiotics

Question 28.
The concept of AG° of coupled reactions f is used to explain reductions in metallurgy.
a. Explain the above statement?
b. In the blast furnace for manufacturing iron, most of the reduction is carried out by CO rather than C (coke). How can you account for this?

Question 29.
a. LDPE is a homopolymer, while Nylon66 is a copolymer. Explain?
b. Classify the following into homopolymer or copolymers. Nylon-66 and HDPE

(Questions 30 to 33): Answer any three. Each questions carries four scores.

Question 30.
Detergents are used to remove oil and dirt from surfaces.
a. What are synthetic detergents? Give an example.
b. What are anionic, cationic and nonionic detergents? Illustrate with examples?
c. A synthetic detergent is used as a dishwasher. To which of the above type would it belong?

Question 31.
Crystal defects give rise to certain special properties in the solids.
a. What is meant by Frenkel defect?
b. VWiy does Li Cl not exhibit Frenkel defect?
c. Explain the pink color of LiCI when heated in the vapors of Li.

Question 32.
The hydrolysis of an ester in acid medium is a first order reaction.
a. What do you mean by an Ist order reaction?
b. What is the relation between the rate of the instant and half-life period of a reaction?
c. Half-life period of a first-order reaction is 20 seconds. How much time will it take to complete 90% of the reaction?

Question 33.
The limiting molar conductivity of an electrolyte is obtained by adding the limiting molar conductivities of cation and anion of the. electrolyte.
a. Name the above law.
b. What is meant by limiting molar conductivity?
c. Explain how conductivity measurements help to determine the ionization constant of a weak electrolyte like acetic add.
d. Explain the change of conductivity and molar conductivity of a solution with dilution?

Answers

Answer 1.
Frenkel defect

Answer 2.
4

Answer 3.
Primary cell

Answer 4.
3

Answer 5.
Froth flotation process

Answer 6.
d

Answer 7.
a

Answer 8.
i. c. Ice I
ii. In primitive unit cells, constituent particles are present only on the corner position I of unit cell whereas in centered unit cell, one or more constituent particles are present at a position other than corners in addition to those at corners.

Answer 9.
i. d. None of these
ii. Conductance (C) is the reciprocal of the resistance (R). C = 1/R

Answer 10.

Answer 11.

Answer 12.

ii. Kolbe’s electrolysis: By the electrolysis of aqueous solution of sodium salt of the propanoic acid.

Butane is formed at the anode.

Answer 13.

Answer 14.
i. Grignard reagent -R MgX
ii. The alkyl halide is treated with magnesium in dry ether to get Grignard reagents.

Answer 15.
i. Antiferromagnetic.
ii. Ferrimagnetic.
iii. Ferromagnetic.

Answer 16.
i. Oxidation: Aldehydes on oxidation give carboxylic acid containing same no. of C atoms.

Ketones on oxidation give a mixture of carboxylic acids containing lesser no.of carbon atoms.

ii. Zn amalgam and HCI for Clemmensen reduction. Hydrazine heated with KOH in ethylene glycol for WolfKishner reduction.

Answer 17.

Answer 18.
a. Haematite, magnetite , Iron pyrites,
b. Bauxite.

Answer 19.
K = ln A – \(\frac { { E }_{ a } }{ RT }\);
where K = Rate constant,
A = Arrhenius factor, E_a = Activation energy, T= Temperature, R = Gas constant

Answer 20.
i. Use of chemicals for therapeutic effect is called chemotherapy.

Answer 21.
a. i. The variation in the amount of gas adsorbed by the adsorbent with pressure at constant temperature is expressed using a curve called adsorption isotherm.
ii. \(\frac { X }{ m } =k.{ p }^{ 1/2 },n>1;\)
where x/m is the extent of adsorption, P is the pressure, K and n are constants which depend on the nature of the adsorbent and the gas at a particular temperature.
b. i. Most highly efficient. One molecule of an enzyme may transform one million molecules of the reactant per minute.
ii. Highly specific in nature. Each enzyme is specific for a given reaction.

Answer 22.
i. α – D- glucose, the bond is glycosidic linkage.
ii. An amino acid, a peptide bond is a linkage.
iii. Nucleotide, Bond is a hydrogen bond.

Answer 23.
a. Natural polymer Cellulose, Starch Synthetic polymer PVC, Nylon,
b. Thermoplastics are linear or slightly branched long chain molecules, which can be remolded again and again by heating and cooling. The intermolecular force is intermediate between elastomers and fibers.

Thermosetting are cross-linked or heavily branched molecules. On heating, they undergo extensive cross-links and becomes infusible. They cannot be remolded.

Answer 24.
a. Monosaccharide Glucose, Fructose-Oligosaccharide Maltose, Lactose, Sucrose Polysaccharide Cellulose
b.
i. Starch.

ii. The linkage between units of amino acids in a polypeptide linkage is called peptide linkage.

Answer 25.

Answer 26.
a. Pentaamminesulphatocobait (III) bromide.
b. Primary valence is 3 and secondary valence is 6.
c. Ionization isomerism.

Answer 27.
a. Tranquilizers are used for the treatment of stress and mental diseases.
b. Analgesics reduce pain without causing any disturbance to the nervous system.
c. Antibiotics are drugs used to treat infections in our body. It inhibits the growth of microorganisms.

Answer 28.
a. For the feasibility of a reaction, ΔrG° must be negative. The positive value of ArG° means that the reaction is not spontaneous. This reaction can be made spontaneous by coupling with a reaction having very large ve Gibb’s energy value so that Gibb’s energy for the two combined reactions become ve.
b. A better reducing agent should have a larger ve value for AG°. If coke is used ArG° = 13 KJ/mol and for CO, ArG° = 56.2 KJ/mol Comparing the two values, it is clear that CO is a better reducing agent than C.

Answer 29.
a. If the polymer is formed only one type of monomer units, then it is a homopolymer. LDPE is low-density polyethylene whose monomer is ethylene. Hence it is a homopolymer.
Nylon66 is the polymer containing two different monomer units hexamethylene diamine and adipic acid. Hence it is a copolymer.
b. Nylon6: Homopolymer HDPE: Homopolymer

Answer 30.
a. Synthetic detergents are cleansing agents which have all the properties of soap, but actually, do not contain any soap. They can be used both in soft and hard water.
b.
i. Cationic detergents are quarternary ammonium salts of amines with acetates, Cl or Bras anions. Cationic part posses a long hydrocarbon chain. They are expensive and have germicidal properties used in hair conditioners, eg., Cetyl trimethyl ammonium bromide.
ii. Anionic detergents are sodium salts of sulfonated long chain alcohols or hydrocarbons. The anionic part of the molecule is involved in cleaning action. Used in toothpaste, household work, eg., sodium dodecyl benzene sulphonate.
iii. Nonionic detergents do not contain any ion. eg., Detergent formed by stearic acid and polyethylene glycol. Liquid dishwashing detergents are nonionic.
c. It belongs to a nonionic type.

Answer 31.
a. Frenkel defect arises due to the dislocation of a cation from its normal site to an interstitial site.
b. Frenkel defect is shown by crystals with a large difference in size between the anion and cation. In LiCI, the cation and anion have comparable (similar) size. So it will not exhibit Frenkel defect.
c. This is due to metal excess defect due to anionic vacancies. When LiCI is heated in vapors of Li, the Cf ions diffuse to the surface of the crystal creating vacant sites. Instead, the electrons diffuse into the crystal and occupy these anionic sites, forming F centers. These electrons absorb energy from white light and show a pink color.

Answer 32.
a. If the sum of powers of the concentration terms in the rate expression is one, then the reaction is a first order reaction.

Answer 33.
a. Kohlrausch’s law.
b. It is the molar conductivity of electrolytes at zero concentration or at infinite dilution.
c. The degree of dissociation can be determined by the equation, \(\alpha =\frac { { \lambda }_{ m } }{ { \lambda }_{ 0 }^{ m } }\) To obtain ionisation constant, K_a substitute α in the following equation, \({ K }_{ a }=\frac { { C\alpha }^{ 2 } }{ (1-\alpha ) }\) where C is the concentration a of acetic acid in moles/liter.
d. The conductivity of a solution decreases with a decrease in concentration as the number of ions presents per unit volume of the solution actually decreases. The molar conductivity of electrolytes increases with a decrease in concentration.

Plus Two Chemistry Previous Year Question Papers and Answers

Kerala State Board New Syllabus Plus Two Chemistry Previous Year Question Papers and Answers.

Kerala Plus Two Chemistry Model Question Paper 1 with Answers

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

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• Read the instructions carefully.
• 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 from 1 – 7 Carry 1 Score each. Answer all the questions. (7 × 1 = 7)

Question 1.
The edge length and axial angles of a unit cell are a = b = c and α = β = γ = 90° respectively. Identify the type of Crystal System.
Answer:
Cubic

Question 2.
Name the polymer used for non-stick surface coated utensils.
Answer:
Polytetrafluoroethene/Teflon

Question 3.
Which of the following forms coloured compounds
i) Sc³⁺
ii) Cr²⁺
iii) Zn²⁺
iv) Cu⁺
[Atomic number Sc-21, Cr-24, Zn-30, Cu-29]
Answer:
ii) Cr²⁺

Question 4.
The rate expression of a reaction is Rate = K [A]^1/2 [B]^1/2. Calculate its overall order.
Answer:
Overall order = \(\frac{1}{2}+\frac{3}{2}\) = 2

Question 5.
Among the following amines, identify the one that does not reach with Hinsberg reagent.
i) C₂H₅NH₂
ii) (CH₃)₂NH
iii) (C₂H₅)₂NH
iv) (CH₃)₃N
Answer:
iv) (CH₃)₃N

Question 6.
The Carbohydrate, that is known as ‘animal starch’ is …………
Answer:
Glycogen

Question 7.
Name the class of drug used for the treatment of stress and mental diseases.
Answer:
Tranquilizers

Questions from 8 – 20 Carry 2 Score each. Answer any 10 questions. (10 × 2 = 20)

Question 8.
Write the names and structures of the monomers of the polymer Buna-S.
Answer:
1, 3-Butadiene CH₂=CH-CH=CH₂
Styrene/Vinyl benzene C₆H₅-CH=CH₂

Question 9.
Calculate the packing efficiency in body centred cubic structure.
[Given that r = \(\frac{\sqrt{3}}{4}\)a, where ‘r’ is the radius of sphere and ‘a’ is the edge length of unit cell]
Answer:
In body centred cubic (bcc) structure, total number of atoms per unit cell is 2.
Volume of atoms in the unit cell = 2 × (\(\frac{4}{3}\))πr³
Volume of the cube = a³ = (\(\frac{4}{\sqrt{3}}\)r)³

Question 10.
Write one method for the preparation of sulphur dioxide. How is its presence detected?
Answer:
Sulphur dioxide is obtained when sulphur is burnt in air or oxygen.
S(s) + O₂(g) → SO₂(g)
OR
In the laboratory, it is prepared by treating a sulphite with dilute sulphuric acid.
SO₃^2-(aq) + 2H⁺(aq) → H₂O(l) + SO₂(g)
OR
Industrially, it is produced as a by-product of the roasting of sulphide ores.
4FeS₂(s) + 11O₂(g) → 2Fe₂O₃(s) + 8SO₂(g)
The sulphur dioxide gas decolourises acidified potassium permanganate solution. This is a convenient test for the gas.
5SO₂ + 3MnO₄^– + 2H₂O → 5SO₄^2- + 4H⁺ + 2Mn²⁺

Question 11.
Write the IUPAC names of following compounds.
a) K₃[Fe(CN)₆]
b) Co[Cl₂(en)₂]Cl
Answer:
a) Potassium hexacyanoferrate(III)
b) Dichloridobis(ethane-1, 2-diamine)cobalt(III) chloride

Question 12.
Define van’t Hoff factor ‘i’. What would be the value of ‘i’ for a dilute solution of K₂SO₄ in water?
Answer:
The van’t Hoff factor, ‘i’ is defined as:


K₂SO₄ ionises in water as,
K₂SO₄ → 2K⁺ + SO₄^2-
Therefore, for a dilute solution of K2S04 in water the value of i = 2 + 1 = 3

Question 13.
By taking ethyl bromide as starting material, prepare ethyl iodide and ethyl fluoride.
Answer:
Ethyl bromide is treated with Nal in dry acetone to get ethyl iodide. (Finkelstein reaction)
CH₃CH₂Br + Nal → CH₃CH₂l + NaBr
Ethyl bromide is heated with metallic fluorides such as AgF, Hg₂F₂, CoF₂ or SbF₃ to get ethyl fluoride. (Swarts reaction)
CH₃CH₂Br + AgF → CH₃CH₂F + AgBr

Question 14.
Write the complete reaction representing the disproportionation of benzaldehyde.
Answer:

This reaction is called Cannizzaro reaction.

Question 15.
Vapour pressure of water at 293 K is 17.535 mm Hg. Calculate the vapour pressure of water at 293 K when 25g of glucose is dissolved in 450 g of water.
Answer:
\(p_{1}^{0}\) = 17.535 mm Hg, w₂ = 25g, M₂ = 180g mol^-1, w₁ = 450 g, M₁ = 18 g mol^-1, p, = ?

Therefore, vapour pressure of glucose solution,
p₁ = \(p_{1}^{0}\) – 0.09742
= 17.535 – 0.09742 = 17.4376 mm Hg

Question 16.
Name the products of hydrolysis of sucrose and explain why sucrose is not a reducing sugar.
Answer:
Sucrose on hydrolysis gives equimolar mixture of D-(+)-glucose and D-(-)-fructose.

In sucrose, the two monosaccharide units (glucose and fructose) are held together by a glycosidic linkage between C1 of α – glucose and C2 of β – fructose. Since the reducing groups of glucose and fructose are involved in glycosidic bond formation, sucrose is a non-reducing sugar.

Question 17.
Tertiary butyl bromide react with aqueous NaOH to give tertiary butyl alcohol proceeds via S_N¹ reaction. Write the mechanism of the reaction.
Answer:

Mechanism: This reaction occurs in two steps:
Step I: The polarised C-Br bond undergoes slow cleavage to produce tert-butyl carbocation and a bromide ion.

Step II: The carbocation is attacked by the nucleophile OH^– to form the product, tert-butyl alcohol.

Question 18.
Give the structures of A and B in the following reaction.

Answer:

Question 19.
Match the following

Answer:

Question 20.
Write a simple chemical test to distinguish ethanal from propanone.
Answer:
Tollens’ Test – On warming with Tollens’ reagent ethanal gives a bright silver mirror while propanone will not give silver mirror.
OR
Fehling’s Test – On heating with Fehling’s reagent ethanal gives a reddish brown precipitate while propanone do not respond to this test.

Questions from 21 – 29 Carry 3 Score each. Answer any 7 questions. (7 × 3 = 21)

Question 21.
The resistance of a 0.5 M solution of an electrolyte enclosed between two platinum electrodes 1.5 cm apart and having an area of 2.0 cm² was found to be 30Ω. Calculate the molar conductivity of the solution.
Answer:
M = 0.5 M, l = 1.5 cm, A = 2 cm², R = 30Ω, \(\Lambda_{m}\) = ?

Question 22.
Write notes on different allotropic forms of phosphorous.
Answer:
The important allotropic forms of phosphorus are white, red and black phosphorus.
White phosphorus: white waxy solid, poisonous, insoluble in water but soluble in CS₂, glows in dark, dissolves in boiling NaOH solution in an inert atmosphere giving PH₃.
P₄ + 3NaOH + 3H₂O → PH₃ + 3NaH₂PO₂
It readily catches fire in air to give dense white fumes Of P₄O₁₀.
P₄ + 5O₂ → P₄O₁₀
It consists of discrete tetrahedral P₄ molecules. It is less stable because of angular strain in P₄ molecule where the angles are only 60°.

Red phosphorus: obtained by heating white P at 573K in an inert atmosphere for several days. This when heated under high pressure, a series of phases of black P is formed. It possesses iron grey lustre. It is odourless, non-poisonous, insoluble in water as well as in CS₂, much less reactive than white P, does not glow in dark. It is polymeric, consisting of chains of P₄ tetrahedra linked together as shown:

Black phosphorus: It has two forms, α -Black P and β -Black P.
α -Black P: It is formed when red P is heated in a sealed tube at 803 K, can be sublimed in air, has opaque monoclinic or rhombohedral crystals, does not oxidise in air.
β -Black P: It is prepared by heating white P at 473K under high pressure. It does not burn in air upto 673 K.

Question 23.
Integrated rate equation for a first order reaction.
K = \(\frac{2.303}{t} \log \frac{\left[R_{0}\right]}{[R]}\)
a) Derive an expression for half life of first order reaction.
b) Find the half life of a first order reaction having rate constant K = 5.5 × 10^-14 S^-1.
Answer:
a) For a first order reaction R → P, the rate constant

Question 24.
What are adsorption isotherms? Write the Freundlich adsorption isotherm equation and plot a graph based on it.
Answer:
Adsorption isotherms are curves used to express the variation of the amount of gas adsorbed by the adsorbent with pressure at constant temperature.

The Freundlich adsorption isotherm gives an empirical relationship between the quantity of gas adsorbed by unit mass of solid adsorbent and pressure at a particular temperature. The relationship can be expressed by the equation:
\(\frac{x}{m}=k \cdot P^{1 / n}\)
where x is the mass of the gas adsorbed on mass m of the adsorbent at pressure P, k and n are constants which depend on the nature of the adsorbent and the gas at a particular temperature.

The relationship can be represented in the form of a curve where mass of the gas adsorbed per gram of the adsorbent (x/m ) is plotted against pressure(P).

Question 25.
Describe the steps involved in the manufacture of sulphuric acid by contact process.
Answer:
The Contact process for the manufacture of sulphuric acid involves three steps:
Step 1: Burning of sulphur or sulphide ores in air to generate SO₂.
S(s) + O₂(g) → SO₂(g)
Step 2: Conversion of SO₂ to SO₃ by the reaction with oxygen in the presence of V₂O₅ catalyst at a pressure of 2 bar and a temperature of 720 K.

Step 3: Absorption of SO₃ in H₂SO₄ to give oleum (H₂S₂O₇).
SO₃ + H₂SO₄ → H₂S₂O₇
Dilution of oleum with water gives H₂SO₄ of the desired concentration.

Question 26.
Differentiate ferrimagnetism from paramagnetism and predict the change that takes place to ferrimagnetic substances on heating.
Answer:
Paramagnetism: Magnetic property which arises due the presence of one or more unpaired electrons. Such substances are weakly attracted by the magnetic field. They are magnetised in a magnetic field in the same direction and lose their magnetism in the absence of magnetic field.
e.g. O₂, Cu²⁺, Fe³⁺, Cr³⁺.

Ferrimagnetism: Magnetic property observed when the magnetic moments of the domains in the substance are aligned in parallel and anti-parallel directions in unequal numbers as shown:

They are weakly attracted by magnetic field as compared to ferromagnetic substances.
e.g. Fe₃O₄ (magnetite) and ferrites like MgFe₂O₄ and ZnFe₂O₄.
Ferrimagnetic substances on heating lose ferrimagnetism and become paramagnetic.

Question 27.
a) Draw the structure of dichromate ion.
b) How can dichromate ion be converted to chromate ion?
c) Write examples for the oxidising action of potassium dichromate in acidic medium.
Answer:
a)

b) When an aqueous solution of dichromate is treated with alkali (i.e., by increasing the pH of the medium) it changes to chromate.
Cr₂O₇^2- + 2OH^– → 2CrO₄^2- + H₂O

c) Acidified potassium dichromate oxides iodides to iodine, sulphides to sulphur, tin(II) to tin(IV) and iron(II) to iron(III).

Question 28.
Explain the following
a) Hydraulic washing
b) Zone refining
c) Roasting of ores
Answer:
a) Hydraulic washing: This is a method used for the concentration of ores. It is based on the differences in gravities of the ore and the gangue particles. It is type of gravity separation. Here an upward stream of running water is used to wash the powdered ore. The lighter gangue particles are washed away and the heavier ores are left behind.

b) Zone refining: It is a method used for obtaining extra pure germanium, silicon, boron, gallium and indium. It is based on the principle that the impurities are more soluble in the melt than in the solid state of the metal. Here a circular mobile heater is fixed at one end of a rod of the impure metal.

The molten zone moves along with the heater which is moved forward, the pure metal crystallises out of the melt and the impurities pass on into the adjacent molten zone. This process is repeated several times and the heater is moved in the same direction. At one end, impurities get concentrated. This end is cut off.

c) Roasting of ores: Roasting is used for converting ore to its oxide. It is mainly applied to sulphide ores. Here the ore is heated in a regular supply of air in a furnace at a temperature below the melting point of the metal, e.g.
2ZnS + 3O₂ → 2ZnO + 2SO₂ OR
2PbS + 3O₂ → 2PbO + 2SO₂ OR
2CU₂S + 3O₂ → 2Cu₂O + 2SO₂

Question 29.
Describe the following reactions.
a) Aldol condensation
b) Etard reaction
c) Rosenmund reduction
Answer:
a) Aldol condensation: Aldehydes and ketones having at least one α – hydrogen atom undergo a reaction in the presence of dilute alkali as catalyst to form β – hydroxy aldehydes (aldol) or β – hydroxy ketones (ketol) respectively. The aldol and ketol on heating readily lose water to give α, β – unsaturated aldehydes or ketones respectively.

e.g. Ethanal on treating with dil NaOH gives 3-hydroxy butanal which on heating loses water to give but-2-enal.

b) Etard reaction: When toluene is treated with chromyl chloride (CrO₂Cl₂) in CS₂ a chromium complex is formed which on hydrolysis gives benzaldehyde.

C) Rosenmund reduction: When an acyl chloride(acid chloride) is hydrogenated over catalyst, palladium on barium sulphate the corresponding aldehyde is formed.
e.g. Benzoyl chloride on hydrogenation over catalyst, palladium on barium sulphate gives
benzaldehyde.

Questions from 30 – 33 Carry 4 Score each. Answer any 3 questions. (3 × 4 = 12)

Question 30.
Write chemical equations for the conversion of phenol to acetylsalicylic acid (aspirin).
Answer:

Question 31.
With the help of diagram describe the construction and working of a fuel cell using H₂ and O₂. What are the advantages of fuel cell over conventional cells.
Answer:
In the H₂ – O₂ fuel cell, hydrogen and oxygen are bubbled through porous carbon electrodes into concentrated aqueous NaOH solution. Catalysts like finely divided platinum or palladium metal are incorporated into the electrodes for increasing the rate of electrode reactions.

This cell uses the reaction of hydrogen with oxygen to form water. The electrode reactions are:
Anode reaction: 2H₂(g) + 4OH^–(aq) → 4H₂O(l) + 4e^–
Cathode reaction: O₂(g) + 2H₂O(l) + 4e^– → 40H^–(aq)
The overall reaction is, 2H₂(g) + O₂(g) → 2H₂O(l)

Advantages:

• The cell runs continuously as long as the reactants are supplied.
• Fuel cells produce electricity with an efficiency of about 70%, which is much higher than that of conventional cells.
• Fuel cells are pollution free.

Question 32.
Sketch the Crystal field splitting of d-orbitals of the Central metal ion in [CoF₆]^3-. Also write the electronic configuration of central metal ion and predict its magnetic behaviour based on Crystal field theory.
Answer:

The electronic configuration of the central metal ion. Co³⁺ is [Ar]3d⁶ 4s⁰.
Here F- is a weak field ligand. Therefore, Δ₀ < P and no pairing occurs (\(t_{2 g}^{4} e_{g}^{2}\)). Thus, there are four unpaired electrons and hence [CoF₆]^3- is an outer orbital/high spin/spin free paramagnetic octahedral complex.

Question 33.
Give the structures and IUPAC names of the products formed on the following reactions.
a) Hydration of propene in the presence of dilute sulphuric acid.
b) Reaction of methanal with methyl magnesium bromide followed by hydrolysis.
Answer:

Kerala Plus Two Chemistry 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 of 2 hrs.
• You are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and the only internal choice is allowed.
• When you select a question, all the subquestions must be answered from the same question itself.
• 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 nonprogrammable calculators are not allowed in the Examination Hall.

Question 1.
a. Identify the nonstoichiometric defect
i. Schottky defect
ii. Frenkel defect
iii. interstitial defect
iv. Metal deficiency defect
b. What type of substance could make better permanent magnets ferromagnetic or ferrimagnetic? Justify your answer.
c. In terms of Band theory write the differences between conductors and insulators.

Question 2.
a. Henry’slaw is related to the solubility of a gas in a liquid.
i. State Henry’s law
ii. Write any two applications of Henry’s law.
b. 1000 cm³ of an aqueous solution of a protein contains 1.26 gm of the protein. The osmotic pressure of such a solution at 300 K is found to be 2.57 × 10^-3 bar. Calculate the molar mass of the protein. (R = 0.083 L bar mol¹K¹)

Question 3.
a. Represent the galvanic cell based on the cell reaction given below:

b. Write the half-cell reactions of the above cell.
c. \(\wedge _{ m }^{ 0 }\) for NaCl, HCl and NaAc are 126.4, 425.9 and 91.0 S cm2 mol^-1 respectively. Calculate \(\wedge _{ m }^{ 0 }\) for HAc.

Question 4.
a. Plot a graph showing variation in the concentration of reactants against time for a zero order reaction.
b. What do you mean by zero order reaction?
c. The initial concentration of the first order reaction, N₂O_5(g) → 2NO_2(g) + 1/2O_2(g) was 1.24 × 10^-2 mol L^-1 at 300 K. The concentration of N₂O₅ after ‘ 1 ’ hour was 0.20 × 10^-10 mol L^-1. Calculate the rate constant of the reaction of 300 k.

Question 5.
There are mainly two types of adsorption. They are physisorption and chemisorption.
a. Differentiate between physisorption and chemisorption.
b. Write any two applications of adsorption.

Question 6.
Leaching is a process of concentration of ores. Explain the leaching of alumina from bauxite.

Question 7.
Nitrogen forms a number of oxides and oxoacids.
a. Which of the following is a neutral oxide of nitrogen?
i. N₂O
ii. N₂O₅
iii. NO₂
iv.N₂O₄
b. Prepare a short write-up on Nitric acid highlighting its laboratory preparation, chemical properties and uses.
OR
Phosphorous forms a number of compounds, a. The gas liberated when calcium phosphide is treated with dil.HC/ is
i. Cl₂
ii.H₂
iii. PH₃
iv. All of the above
b. Prepare a short write up on PCl₃ and PCl₅ highlighting the preparation and chemical properties of PCl₃ and structure of PCl_r

Question 8.
a. Transition elements are d block elements.
i. Write any four characteristic properties of transition elements.
ii Cr²⁺ and Mn³⁺ have d⁴ configuration. But Cr²⁺ is reducing and Mn³ is oxidizing. Why?
b. Which of the following is not a lanthanoid element?
i. Cerium
ii. Europium
iii Lutetium
iv. Thorium

Question 9.
[CO(NH₃)₅S0₄]Cl and [Co(NH₃)₅ Cl]SO₄ are coordination compounds.
a. Identify the isomerism shown by the above compounds.
b. Write the IUPAC names of the above compounds.
c. Identify the ligands in each of the above compounds.

Question 10.
a. An ambident nucleophile is
i. Ammonia
ii Ammonium ion
iii Chloride ion
iv. Nitrite ion
b.Haloalkanes and Haloarenes are organohalogen compounds.
i. Suggest a method for the preparation of alkyl chloride.
ii. Aryl halides are less reactive towards Nucleophilic substitution reactions. Give reasons.

Question 11.
a. Arrange the following compounds in the order of increasing boiling points: Ethanol, Propan1 o 1, Butan1 o 1, Butan2ol
b. In the lab, students were asked to carry out the reaction between phenol and cone. HN03. But one student, ‘A’ carried out the reaction between phenol and dil. HNOr Do you think that the student ‘A’ got the same result as others. Substantiate with suitable explanations. [Also write the chemical equations wherever necessary]

Question 12.
a. The product obtained when benzene is treated with carbon monoxide and hydrogen chloride in presence of anhydrous AlCl₃ is
i. Chlorobenzene
ii. Phenol
iii. Benzaldehyde
iv. Benzoic acid
b. How will you carry out the following conversions?

OR

b. Explain the following:
i. Esterification
ii. Tollen’s test
iii. HVZ reaction
iv. Dicarboxylic acid

Question 13.
a. Classify the following amines as primary, secondary and tertiary

Identify the products B and C and write their formulae.

Question 14.
a. Which of the following is a polysaccharide?
i. Maltose
ii. Sucrose
iii. Fructose
iv. Cellulose
b. Explain the amphoteric behavior of amino acid.

Question 15.
a. Which of the following is not applicable to Nylon 6, 6?
i. Synthetic polymer
ii. Fiber
iii. Addition polymer
iv. Condensation polymer.
b. Differentiate between thermoplastics and thermosetting plastics. Write one example for each.

Question 16.
‘Antibiotics, antiseptics, and disinfectants are antimicrobial drugs. Explain any one of the above-mentioned drugs with examples.

Answers

Answer 1:
a. Metal deficiency defect
b. Ferromagnetic substances make better permanent magnets because, in the solid state, the metal ions of ferromagnetic substances are grouped together into small regions called domains. Thus, each domain acts as a tiny magnet. In an unmagnetized piece of a ferromagnetic substance, the domains are randomly oriented and their magnetic moments get canceled. When the substance is placed in the magnetic field, a strong magnetic effect is produced. This ordering of domains persists even when the magnetic field is removed and the ferromagnetic substance becomes a permanent magnet. However, this is not possible in ferrimagnetic substances,

c. In conductors, the valence band and conduction band overlap. Hence electrons can easily flow. In insulators the energy gap between the valence band and the conduction band is large, hence electrons cannot jump from one band to the other.

Answer 2.
a. i. It states that “the solubility of a gas in a liquid is directly proportional to the partial pressure of the gas present above the surface of liquid or solution”. The most commonly used form of Henry’s law states that “the partial pressure(p) of gas in the vapor phase is proportional to the mole fraction of the gas(x) in the solution” and it is expressed as, P = K_H.X, where KH is Henry’s law constant and ‘x’, is mole fraction of gas in solution.
ii.
1. To increase the solubility of CO2 in soda water and soft drinks, the bottle is sealed under high pressure.
2. To avoid the toxic effects of a high concentration of nitrogen in blood, the tanks used by scuba divers are filled with air diluted with helium.
b. p = 2.57 × 10^-3 bar
V = 1000 cm³ = 1L
T = 300k
R = 0.083 L bar mol^-1K^-1

Answer 3.

Answer 4.
a.

b. In zero order reactions, the rate remains constant throughout the course of reaction i.e., the rate does not change with a change in concentration of reactants.

Answer 5.
a. Physical adsorption (Physisorption):

• Force of attraction between adsorbate and adsorbent are Van der Waals forces.
• Lacks specificity.
• Reversible.
• Enthalpy of ads 40kJmol^-1)
• Occurs at low temperature.

Chemical adsorption (chemisorption):

• Force of attraction I and adsorbent I bonds.
• Highly specific.
• Irreversible.
• Enthalpy of advisor 240kJ/mol).
• Occurs at high terr

b.

• Production of high
• Gas masks
• Heterogenous cat?
• Froth floatation pr
• Control of humidity;
• Chromatographic analysis

Answer 6.
Bauxite ore is treated with aqueous NaOH at 473-523K and 35-36 bar pressure. This way Al₂O₃ is leached out as sodium aluminate leaving the impurities behind.

The aluminate in solution is neutralized by passing C0₂ gas and hydrated Al₂O₃ is precipitated.

The sodium silicate remains in the solution and hydrated alumina is filtered, dried and heated to give back pure Al₂O₃

Another example: Gold or silver ore is leached with a dilute solution of NaCN or KCN in the presence of air from which the metal is obtained by replacement (using Zn as a reducing agent).

Answer 7.
a. N₂O
b. In the laboratory, nitric acid is prepared by heating KNO₃ or NaNO₃ and concentrated H₂SO₄ in a glass retort.

On large scale, it is prepared mainly by Ostwald’s process. This method is based upon catalytic oxidation of NH₃ by atmospheric oxygen.

Nitric oxide thus formed combines with oxygen giving NO₂,

Nitrogen dioxide so formed dissolves in water to give HN03.

NO thus formed is recycled and the aqueous HNO₃ can be concentrated by distillation up to 68% by mass. Further concentration to 98% can be achieved by dehydration with concentrated H₂SO₄. Chemical properties
1. Acidic nature

2. Oxidizing agent behaves as a strong oxidizing agent because of its tendency to give nascent oxygen.

Uses :
Used in the manufacture of various fertilizers, explosives, plastics, fibers, dyestuffs etc. It is used as a laboratory reagent and as an oxidizing agent. It is also used in the purification of silver an gold.
OR
a. (iii) pH₃
b. Phosphorus forms two types of halides, PX₃ (X = F, Cl, Br, I) and PX₅ (X = F, Cl, Br). Preparation
It is obtained by passing dry chlorine overheated white phosphorus. P₄ + 6CI₂ → 4PCI₃ It is also obtained by the action of thionyl chloride with white phosphorus. P₄ + 8SOCI₂ → 4PCI₃ + 4SO₂ + 2S₂CI₂ Properties It is a colorless oily liquid and hydrolyzes in the presence of moisture.
PCI₃ + 3H₂O → H₃PO₃ + 3HCI It reacts with organic compounds containing OH group such as CH₃COOH, C₂H₅OH.
3CH₃COOH + PCI₃ → 3CH₃COCI + H₃PO₃ 3C₂H₅OH + PCI₃ → 3C₂H₅CI + H₃PO₃ It has a pyramidal shape as shown, in which phosphorus is sp3 hybridized. Preparation
Phosphorus pentachloride is prepared by the reaction of white phosphorus with an excess of dry chlorine. P₄ + 10Cl₂ → 4PCL₅
It can also be prepared by the action of SO₂CI₂ on phosphorus.
P₄ + 10SO₂CI₂ → 4PCI₃ + 10SO₅Properties PCI₅ is a yellowish white powder and in moist air, it hydrolyzes to POCI₃ and finally gets converted to phosphoric acid. PCI₅ + H₂O → POCI₃ + 2HCI POCI₃ + 3HO → HPO₄ + 3HCI In gaseous and liquid phases, it has a trigonal bipyramidal structure as shown. The three equatorial P_CI bonds are equivalent, while the two axial bonds are longer than equatorial bonds.

This is due to the fact that the axial bond pairs suffer more repulsion as compared to equatorial bond pairs. In the solid state, it exists as an ionic solid, [PCI₄]⁺ [PCI₆]^– in which the cation, [PCI₄]⁺ is tetrahedral and the anion, [PCI₈]^– cathedral.

Answer 8.
a. i. The transition elements are those elements which have partially filled subshells in their elementary form or in any one of its oxidation states. They have low ionization energy. They are malleable and ductile. They are good conductors of heat and electricity. High melting and boiling point.
ii. Cr²⁺ is reducing as its configuration changes from d⁴ to d³, the latter having a half-filled t_2g level. On the other hand, the change from Mn²⁺ results in the half-filled (d⁵) configuration which has extra stability,
b. Thorium

Answer 9.
a. Ionization isomerism
b. [C0(NH₃)₅S0₄]CI- Pentaamminesulphatocobalt (III) chloride [CO(NH₃)₅Cl]SO₄ – Pentamminechloridocobalt (III) sulfate
c. Counterion in a complex salt itself a potential ligand. ligands are Ct and SO₄^2-

Answer 10.
a.iv. Nitrite ion
b.i. The preparation of alkyl chloride is carried out either by passing dry hydrogen chloride gas through a solution of alcohol or by heating a solution of alcohol in concentrated aqueous acid.

ii.
1. Aryl halides are electron rich.
2. In aryl halides, the halogen is attached to an sp² hybridized C, which is highly stable.
3. Because of the possible repulsion, it is less likely for the electron-rich arenes.
4. In the case of haloarenes, the phenyl cation formed as a result of self-ionization will not be stabilized by resonance and therefore, SN, a mechanism is ruled out.

Answer 11.
a. Ethanol < Propane -l-ol < Butan 2-ol < Butan -1-ol.
b. They don’t get the same result. Phenol with dilute nitric acid at low temperature (298 K) phenol yields a mixture of ortho and para nitrophenols.

Phenol with concentrated nitric acid, phenol is converted to 2, 4, 6 trinitrophenol. The product is commonly known as picric acid. The yield of the reaction product is poor.

Answer 12.
a. (iii) Benzaldehyde


OR
b.
i. Carboxylic acids react with alcohols in the presence of a strong acid catalyst like H₂SO₄ to form esters. The reaction is reversible and the forward reaction is called esterification,

ii. On warming an aldehyde with freshly prepared ammoniacal silver nitrate solution (Tollen’s reagent) a bright silver mirror is produced due to the formation of silver metal. The aldehydes are oxidized to corresponding carboxylate anion. The reaction occurs in alkaline medium.

iii. HVZ reaction
Carboxylic acids having an α – hydrogen is halogenated at the α – position on treatment with chlorine or bromine in the presence of small amount of red phosphorous to give α – halocarboxylic acids. The reaction is known as Hell Volhard Zelinsky reaction.
iv. Carboxylic acids lose carbon dioxide to form hydrocarbons when their

Sodium salts are heated with soda lime (NaOH and CaO in the ratio of 3:1). The reaction is known as decarboxylation.

Answer 13.

Answer 14.
a.iv. Cellulose
b. In aqueous solution, the carboxyl group can lose a proton and amino group can accept a proton, giving rise to a dipolar ion known as twitter ion. This is neutral but contains both positive and negative charges. In winter ionic form amino acids show amphoteric behavior as they react both with acids and bases.

Answer 15.
a.iii. Addition polymer
b. Thermoplastic polymers These are the linear or slightly branched long chain molecules capable of repeatedly softening on heating and hardening on cooling. These polymers possess intermolecular forces of attraction intermediate between elastomers and fibers. Some common thermoplastics are polyethylene, polystyrene, polyvinyls, etc.

Thermosetting polymers These polymers are cross-linked or heavily branched molecules, which on heating undergo extensive cross-linking in molds and again become infusible. These cannot be reused. Some common examples are bakelite, urea formaldehyde resins, etc

Answer 16.
Antibiotics: These are chemical substances which are produced wholly or partly by chemical synthesis, which in low concentration inhibits the growth or destroys microorganisms by intervening in their metabolic processes, eg., penicillin, streptomycin, ampicillin, tetracycline. Antibiotics are of two types:
Bactericidal antibiotics: They have killing (cidal) effect on microbes, eg., pencil in, ofloxacin, etc.
Bacteriostatic antibiotics: They have an inhibitory (static) effect on microbes, eg., Tetracycline, chloramphenicol, etc.
Antibiotic spectrum: The range of microorganisms attacked by an antibiotic is called its spectrum.

• Antibiotics which kill or inhibit a wide range of Gram-positive and Gram-negative bacteria are called broad-spectrum antibiotics.
  eg., Ampicillin, tetracycline, ofloxacin.
• Those which are effective mainly against Gram-positive or Gram-negative bacteria are narrow spectrum antibiotics.
  eg., penicillin G.

Plus Two Chemistry Previous Year Question Papers and Answers

Kerala State Board New Syllabus Plus Two Chemistry Previous Year Question Papers and Answers.

Kerala Plus Two Chemistry Previous Year Question Paper March 2018 with Answers

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

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• Read the instructions carefully.
• 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 one score each. Answer all questions. (Scores: 7 × 1 = 7)

Question 1.
What is the co-ordination number of particles present in FCC crystal structure?
Answer:
12

Question 2.
Identify the order of reaction if the unit of rate constant is mol L^-1s^-1.
Answer:
Zero order

Question 3.
What is the structure of chromate ion ((CrO₄)2-)?
Answer:
Tetrahedral
OR

Question 4.
Name the test used to identify primary amines using CHCl₃ and ethanolic KOH.
Answer:
Carbylamine test/reaction or Isocyanide test

Question 5.
Which among the given vitamins is water soluble?
a) A
b) B
c) D
d) E
Answer:
b) B

Question 6.
What is the crosslinked polymer obtained by the polymerisation of phenol and formaldehyde?
Answer:
Bakelite

Question 7.
……….. is an artificial sweetener which is unstable at cooking temperature.
Answer:
Aspartame

(Questions 8 to 20): Answer any ten. Each question carries two scores. (Scores: 10 × 2 = 20)

Question 8.
a) Based on the nature of intermolecular forces, classify the following solids:
i) SiO₂
ii) Ice
b) ZnO turns yellow on heating. Why?
Answer:
a) i) SiO₂ – Covalent/Network solid
ii) Ice – Molecular slod/Hydrogen bonded molecular solid.

b) This is due to metal excess defect caused by the presence of extra cations at interstitial sites. ZnO is white in colour at room temperature. On heating it loses oxygen as,

The excess Zn²⁺ ions move to interstitial sites and electrons to neighbouring interstitial sites which imparts yellow colour to the crystal.

Question 9.
A solution contains 15g urea (molar mass = 60 g mol^-1) per litre of solution in water has the same osmotic pressure as a solution of glucose (molar mass =180 g mol^-1) in water. Calculate the mass of glucose present in one litre of its solution.
Answer:
πV = nRT
or π = \(\frac{n R T}{V}\)
Let π₁ be the osmotic pressure of urea and π₂ that of glucose. Then,

Here the two solutions are isotonic i.e., have same osmotic pressure.
Therefore, π₁ = π₂

Question 10.
Define minimum boiling azeotropes with example.
Answer:
Azeotropes are binary mixtures having the same composition in liquid and vapour phase and boil at a constant temperature. The solutions which show large positive deviation from Raoult’s law form minimum boiling azeotrope at a specific composition.
e.g. a 95% (v/v) solution of ethanol in water.

Question 11.
Write the chemical equation of the following reactions:
a) Preparation of XeO₃ from XeF₆.
b) Mixing PtF₆ and Xe.
Answer:
a) XeF₆ + 3H₂O → XeO₃ + 6HF
b) Xe + PtF₆ → Xe + PtF₆^–

Question 12.
Explain how the complexes of nickel, [Ni(CN)₄]² and [Ni(CO)₄] have different structures, but do not differ in their magnetic behaviour. (Ni, Atomic No: 28)
Answer:
In [Ni(CN)₄]^2-, Ni (3d⁸ 4s²) is in +2 oxidation state (Ni²⁺ – 3d⁸) and it undergoes dsp² hybridisation. So the ion has square planar geometry. But in [Ni(CO)₄], Ni is in 0 oxidation state and it undergoes sp³ hybridisation. So it has tetrahedral geometry. Due to the absence of unpaired electrons both the complexes are diamagnetic.

Question 13.
Complete the reaction:

Answer:

Question 14.
During the β-elimination reaction of 2-bromopentane in an alcoholic solution of KOH results Pent-2-ene as major product and Pent-1-ene as minor product. State the rule to explain the reaction.
Answer:
Zaitsev rule/Saytzeff rule. The rule states that “in dehydrohalogenation reactions, if there is a possibility of formation of more than one alkene, the preferred product is that alkene which has the greater number of alkyl groups attached to the doubly bonded carbon atoms.”

Question 15.
Aromatic aldehydes undergo electrophilic substitution reactions. Write the nitration reaction of benzaldehyde with chemical equation.
Answer:
The -CHO group being a meta-directing group, benzaldehyde on nitration gives m-nitrobenzaldehyde.

Question 16.
Briefly describe Gatterman Koch reaction.
Answer:
Gatterman – Koch reaction: When benzene or its derivative is treated with carbon monoxide and hydrogen chloride in the presence of anhydrous aluminium chloride or cuprous chloride, it gives benzaldehyde or substituted benzaldehyde.

Question 17.
How can it convert methyl iodide to ethanamine?
Answer:
Methyl iodide when treated with KCN or NaCN gives methyl cyanide or ethane nitrile which on reduction with LiAlH₄ or H₂ in presence of Ni/Pt/Pd or by sodium amalgam and ethanol we get ethanamine.

Question 18.
State two differences between globular and fibrous proteins.
Answer:
Globular proteins:

1. Polypeptide chains coil around.
2. Spherical shape.
3. Soluble in water.

Fibrous proteins:

1. Polypeptide chains run parallel and held together by hydrogen and disulphide bonds.
2. Fibre-like structure.
3. Insoluble in water.

Question 19.
Match the following:

Answer:

Question 20.
a) What are drugs?
b) Write an example for a drug classified based on its chemical structure.
Answer:
a) Drugs are chemicals of low molecular mass (~ 100 – 500u) which interact with macro molecular targets and produce a biological response.
b) Sulphonamides or Sulpha drugs like arsphenamine/salvarsan, prontosil, sulphapyridine.

(Questions 21 to 29): Answer any seven. Each question carries three scores: (Scores: 7 × 3 = 21)

Question 21.
An element crystallises as FCC with density 2.8 gm³. Its unit cell having edge length 4 × 10^-8 cm. Calculate the molar mass of the element. (Given N_A = 6.022 × 10²³ mol^-1)
Answer:
d = 2.8 g cm^-3, a = 4 × 10^-8 cm, z = 4 (since unit cell is FCC), N_A = 6.022 × 10²³ mol^-1.
Density, d = \(\frac{\mathrm{zM}}{\mathrm{a}^{3} \mathrm{~N}_{\mathrm{A}}}\)
Molar mass of the element, M = \(\frac{\mathrm{da}^{3} \mathrm{~N}_{\mathrm{A}}}{\mathrm{z}}\)

Question 22.
Write the anode and cathode reactions occur in the operation of a lead storage battery. Mention the electrolyte used in the battery.
Answer:
Anode reaction: Pb(s) + SO₄^2- (aq) → PbSO₄(s) + 2e^–
Cathode reaction: PbO₂(s) + SO₄^2- (aq) + 4H⁺(aq) + 2e^– → PbSO₄(s) + 2H₂O(l)
Electrolyte: 38% solution of sulphuric acid.

Question 23.
For hydrolysis of methyl acetate in aqueous solution, the following results were observed.

Show that it follows pseudo first order reaction as the concentration of water remains constant.
Answer:
As the concentration of water remains constant, practically the reaction should be pseudo first order with respect to methyl acetate.

The rate constant for a pseudo first order reaction,

From the above results it can be seen that k = k’ [H₂O] is a constant and hence, it is a pseudo first order reaction.

Question 24.
a) State Hardy-Schulze rule with the help of example.
b) Why lyophilic colloids are used as protective colloids?
Answer:
a) The Hardy-Schulze rule states that the greater the valence of the flocculating ion added, the greater is its power to cause precipitation.
For example, in the coagulation of a negative sol like AS₂S₃, the flocculating power is in the order: Al³⁺ > Ba²⁺ > Na⁺
Or, in the coagulation of a positive sol like Fe₂O₃.xH₂O, the flocculating power is in the order:
[Fe(CN)₆]^4- > PO₄^3- > SO₄^2- > Cl^–

b) Lyophilic colloids have a unique property of protecting lyophobic colloids. When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around lyophobic particles and thus protect the lyophobic sols from electrolysis.

Question 25.
Gibbs energy of formation (Δ_fG) of MgO(s) and CO(g) at 1273 K and 2273 K are given below:
(Δ_fG) [MgO(s)]: -941 kJ mol^-1 at 1273 K

On the basis of the above data, predict the temperature at which carbon can be used as a reducing agent for MgO(s)
Answer:
As per the Ellingham diagram, for using carbon as a reducing agent for MgO(s), the value of Δ_rG for the coupled reaction, MgO(s) + C(s) → Mg(s) + CO(g) should be negative at the required temperature.
Given that, at 1273 K
i) Mg(s) + \(\frac{1}{2}\)O₂(g) → MgO(s); Δ_fG = -941 kJ mol^-1
ii) C(s) + \(\frac{1}{2}\)O₂(g) → CO(g); Δ_fG = -439 kJ mol^-1
On reversing equation (i) and adding with equation (ii), we get
MgO(s) + C(s) → Mg(s) + CO(g); Δ_rG = (941 + – 439) kJ mol^-1 = +502 kJ mol^-1
Since Δ_rG is positive, carbon cannot be used as a reducing agent for MgO(s) at 1273 K.
Given that, at 2273 K
iii) Mg(s) + \(\frac{1}{2}\)O₂(g) → MgO(s); Δ_fG = -314 kJ mol^-1
iv) C(s) + \(\frac{1}{2}\)O₂(g) → CO(g); Δ_fG = -628 kJ mol^-1
On reversing equation (iii) and adding with equation (iv), we get
MgO(s) + C(s) → Mg(s) + CO(g); Δ_rG = (314 + – 628) kJ mol^-1 = -314 kJ mol^-1
Since Δ_rG is negative, carbon can be used as a reducing agent for MgO(s) at 2273 K.

Question 26.
a) What is the formula of the phosphine?
b) How phosphine is prepared in laboratory?
Answer:
a) PH₃
b) In the laboratory, phosphine is prepared by heating white phosphorus with concentrated NaOH solution in an inert atmosphere of CO₂.
P4 + 3NaOH + 3H₂O → PH₃ + 3NaH₂PO₂
(Or, any other laboratory method of preparation of PH₃.)

Question 27.
Assign the possible reason for following:
a) Stability of +5 oxidation state decreases and that of +3 oxidation state increases down to 15^th group elements.
b) H₂O is less acidic than H₂S.
c) H₃PO₂ act as a good reducing agent while H₃PO₄ does not.
Answer:
a) It is due to inert pair effect. In the case of heavier elements the lowest oxidation states are more prodominent due to non-participation of the s-electrons in the formation of bonds.

b) In the case of the hydrides (H₂E) of group 16 elements, down the group the H-E bond dissociation enthalpy decreases and hence acidic character increases. Due to small size of O compared to that of S, the O-H bond dissociation enthalpy is greater than the S-H bond dissociation enthalpy. Hence, H₂O is less acidic than H₂S.

c) The reducing property of oxoacids of phosphorus depends on the P-H bond. The acids which contain P-H bond have strong reducing properties. Thus, H₃PO₂ is a good reducing agent as it contains two P-H bonds. H₃PO₄ has no P-H bonds and hence it has no reducing property.

Question 28.
Give reasons for the following:
a) Transition metals and many of their compounds act as catalyst.
b) Scandium (Z = 21) does not exhibit variable oxidation state and yet it is regarded as a transition element.
c) Write the step involved in the preparation of Na₂CrO₄ from chromite ore.
Answer:
a) Transition metals and their compounds are known for their catalytic activity. This is due to their ability to adopt multiple oxidation states and to form complexes. Thus they can form with lower activation energy for the reaction. Also because the transition metal ions can change their oxidation states, they become more effective as catalysts.

In some cases transition metals provide a suitable surface for the reaction to take place. The reactants are adsorbed on the surface of the catalyst where reaction occurs. This has the effect of increasing the concentration of the reactants at the catalyst surface and also weakening of the bonds in the reacting molecules.

b) Scandium is regarded as a transition element because it has incompletely filled 3d orbitals in the ground state of the atom (3d¹ 4s²).

c) The chromite ore is fused with sodium carbonate or potassium carbonate in free access of air.
4FeCr₂O₄ + 8Na₂CO₃ + 7O₂ → 8Na₂CrO₄ + Fe₂O₃ + 8CO₂

Question 29.
How would you account for the following:
a) Aldehydes are more reactive than ketones towards nucleophilic addition reaction.
b) Boiling point of aldehydes are lower than alcohols.
c) Addition reaction of sodium hydrogen sulphite is useful for separation and purification of aldehydes.
Answer:
a) This is due to steric and electronic reasons.
Sterically, the presence of two relatively large substituents in ketones hinders the approach of nucleophile to carbonyl carbon that in aldehydes having only one such substituent.

Electronically, the two alkyl groups reduce the electrophilicity of the carbonyl carbon more effectively in ketones than in aldehydes.

b) The boiling points of aldehydes are lower than those of alcohols of comparable molecular masses due to the absence of intermolecular hydrogen bonding in aldehydes where as alcohols can associate through intermolecular hydrogen bonding and have higher boiling points.

c) The hydrogen sulphite addition compound is water soluble and can be converted back to the original aldehyde by treating it with dilute mineral acid or alkali. Therefore, these are useful for separation and purification of aldehydes.

(Questions 30 to 33): Answer any three. Each question carries four scores: (Score: 3 × 4 = 12)

Question 30.
a) What are primary batteries?
b) The cell potential of a mercury cell is 1.35 V, and remain constant during its life. Give reason.
c) Write the equation of the reactions involved at each electrode in a H₂-O₂ fuel cell.
Answer:
a) Batteries in which the reaction occurs only once and after use over a period of time they become dead and cannot be reused again.
b) This is because the overall reaction does not involve any ion in solution whose concentration can change during its life time.
c) Anode reaction: 2H₂(g) + 4OH^– (aq) → 4H₂O(l) + 4e^–
Cathode reaction: O₂(g) + 2H₂O(l) + 4e^– → 4OH^– (aq)

Question 31.
a) Draw the structures of geometrical isomers of [Fe(NH₃)₂(CN)₄]^–
b) Write the formula of pentaammine carbonate cobalt (III) chloride.
c) Wife any two limitations of valance bond theory.
Answer:
a)

b) [Co(NH₃)₅(CO₃)]Cl

c) i) It involves a number of assumptions.
ii) It does not give quantitative interpretation of magnetic data.
iii) It does not explain the colour exhibited by coordination compounds.
iv) It does not give a quantitative interpretation of the thermodynamic or kinetic stabilities of coordination compounds.
v) It does not make exact predictions regarding the tetrahedral and square planar structures of 4-coordinate complexes
vi) It does not distinguish between weak and strong ligands.
(Any two limitations)

Question 32.
a) Grignard reagents are important class of organometallic compounds used to prepare alcohols. Identify the compounds A and B and write the formula.


b) Write the name of products formed when salicylic acid is treated with acetic anhydride in acid medium
Answer:
a) i) Compound A : Ethanol/Ethyl alcohol – CH₃CH₂OH
ii) Compound B : Ethanal/Acetaldehyde – CH₃CHO
b) Acetylsalicylic acid/Aspirin and Acetic acid/Ethanoic acid

Question 33.
Lucas test is used to identify primary, Secondary and tertiary alcohols.
a) Explain the process.
b) Name the reagents used in the test.
Answer:
a) Lucas test – When treated with Lucas reagent, tertiary alcohols give turbidity immediately, secondary alcohols give turbidity within 5 minutes while primary alcohols do not give turbidity at room temperature but only on heating. This test is based upon the relative reactivities of various alcohols towards Lucas reagent. The order of reactivity is, 3° alcohols > 2° alcohols > 1° alcohols. Alcohols are soluble in Lucas reagent and form a clear solution. On reaction, alkyl chlorides are formed which being insoluble result in the development of turbidity,

b) Lucas reagent is a mixture of conc. HCl and anhydrous ZnCl₂.

Kerala Plus Two Physics Model Question Paper 5

Time: 2 Hours
Cool off time : 15 Minutes

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Your are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.
• 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.

Speed of light, c = 3 x 10⁸m/s
Mass of proton, m_p = 1.6726 x 10^-27 kg
Mass of neutron, mn = 1.6749 x 10^-27 kg
Planck’s constant, h = 6.626 x 10^-34 Js
1eV=1.6 x 10^-19 J

Questions 1-7 carry 1 score each. Answer any six questions.

Question 1.
Write the expression for intensity of electric field near to the surface of a charged conductor with uniform charge density σ.

Question 2.
The unit of electrical resistivity is…………

Question 3.
E.m.f can be induced in a coil placed in an external magnetic field by:
a. Changing the intensity of magnetic field
b. Changing the area of coil
c. Changing the orientation of the coil
d. All of the above

Question 4.
Write the energy and momentum associated with a moving photon.

Question 5.
The value of relative permeability of a dia magnetic material is;

Question 6.
The electric field amplitude of an electromagnetic wave is 15V/m. Find the magnetic field amplitude of the wave.

Question 7.
A convex lens is placed in a medium having refractive index greater than that of the lens. The lens now behaves as;
a. Converging lens
b. Diverging lens
c. Plane glass plate
d. None of the above

Questions 8 to 15 carry 2 score each. Answer any 7 questions

Question 8.
a. ‘Electrostatic field is always normal to the surface of a charged conductor’. Justify the statement.
b. The value of electric potential at the surface of a charged conductor is 10 V. Find the value of intensity of electric field and potential at a point interior to it

Question 9.
A galvanometer with a coil of resistance 12 Ω shows a lull scale deflection for a current of 2.5 mA. How can it be converted into an ammeter of range 7.5 A?

Question 10.
The curves shown in figure are drawn for different magnetic materials. Among the three curves, name the curve that

a. Represent the material usually used for making permanent magnets.
b. Represent the material usually used for making electromagnets.

Question 11.
A capacitor C, a variable resistance R and a bulb B are connected in series to a.c mains in the circuit as shown. The bulb glows with some brightness. How the glow of the bulb change if.

a. A dielectric slab is introduced between the plates of the capacitor
b. The resistance R is increased keeping the same capacitance

Question 12.
James Clerk Maxwell modified Ampere’s circuital theorem by introducing the concept of displacement current.
a. What do you mean by displacement current?
b. Write down the equation for displacement current.

Question 13.
An object AB is kept in front of a concave mirror as shown in figure.


a. Complete the ray diagram showing the image formation of object
b. How will the position and intensity of image be affected if the lower half of the mirror’s reflecting surface is painted black?

Question 14.
Assuming that the two diodes D1 and D2 used in the electric circuit as shown in figure are ideal. Find out the value of current flowing through 2.5 Ω resistor.

Question 15.
a. Mention the function of the following used in the communication system
i. Transducer
ii. Transmitter
b. Figure shows the block diagram of a AM transmitter. Identify the boxes X and Y.

Questions 16 to 22 carry 3 scores each. Answer any 6 questions.

Question 16.
Three capacitors of capacitances 2µF, 3µF and 4µF are connected in series.
a. Find the equivalent capacitance of the combination.
b. The plates of a parallel plate capacitor have an area 20 cm² each are separated by a distance of 2.5 mm. The capacitor is charged by connecting it to a 400V supply. How much electrostatic energy is stored in the capacitor?

Question 17.
A circuit using potentiometer and a battery of. negligible internal resistance is set up as shown to develop a constant potential gradient along the wire PQ. Two cells of e.m.f s E1 and E2 are connected in series as in figure in combination 1 and 2. The balance points are obtained respectively at 400 cm and 240 cm from point P. Find

Question 18.
A conducting rod PQ of length ‘ l ’ connected to a resistance ‘R’ is moved at a uniform speed ‘ V’, normal to a uniform magnetic field ‘B’

a. Deduce the expression for e.m.f induced in the conductor
b. Find the magnitude and direction of current through the conductor

Question 19.
In tuner circuits, we use the phenomenon of resonance.
a. Write the condition of resonance in series LCR circuit
b. A series LCR circuit uses L = 0. 1 H,C = 10µF and R = 100Ω. Find the value of frequency at which the amplitude of current is maximum

Question 20.
The focal length of a lens has dependence on its radii of curvatures and refractive index. Derive Lens maker’s formula

Question 21.
a. Write the expression for the de Broglie wavelength associated with a charged particle having charge ‘q’ and mass ‘m’, when it is accelerated by a potential of ‘V’ volts.
b. A proton and an electron have same kinetic energy. Which one has greater value of de Broglie wavelength and why?

Question 22.
Find the binding energy per nucleon of ₂₀⁴⁰Ca nucleus. Given m ₂₀⁴⁰Ca = 39.962589u.
m_p = 1.00783u, m_n = 1.00867u
Take 1 amu = 931 MeV/c²

Questions from 23-26 carry 4 score. Answer any 3 questions.

Question 23.
Gauss’s theorem is useful for finding the intensity of electric field.
a. Write the Gauss’s law in its mathematical form
b. Using the law, prove that intensity of electric field at a point due to a uniformly charged infinite plane sheet is independent of the distance from it

Question 24.
a. Express Ohm’s law in terms of current density, electrical resistivity and intensity of electric field
b. Explain the variation of resistance of a semiconductor with temperature. Also draw the graph showing the variation of resistivity of silicon with temperature

Question 25.
The relation between magnetic field and current is given by Biot-Savart’s law.
a. Write the expression for the magnetic field at point along the axis of a circular loop of radius ‘R’ carrying a current ‘I’.
b. From the above expression. Find the value of magnetic field at the centre of the loop
c. Sketch the magnetic field lines for current carrying circular loop

Question 26.

a. Identify the diode in the circuit and write the use of the resistance R_s
b. Explain how the diode helps as to stabilize the output voltage of the circuit
c. Name the type of biasing used in this diode

Questions 27 to 29 carry 5 scores. Answer any 27 – 29 carry 5 score. Answer any 2 questions

Question 27.
In the figure, PQ is the incident ray on the equilateral glass prism ABC.

a. Complete the ray diagram showing the passage of light and mark angle of deviation.
b. Derive an expression for the refractive index of the material of the prism

Question 28.
According to Christian Huygens wave theory, light emanating from a source as wave fronts.
a. What is the shape of wave front emerging form a linear source?
b. Derive the mathematical expression for the bandwidth of interference bands obtained in young’s double slit experiment with the help of suitable diagram

Question 29.
a. The radius of n^th stationary orbit of hydrogen atoms is :

Using Bohr postulates, obtain an expression for the energy of electron in the stationary states of H-atom

b. Draw the energy level diagram showing how the spectral lines corresponding to Balmer series occur due to transition between the energy levels

Answers

Answer 1.
\(E=\frac { \sigma }{ { \varepsilon }_{ 0 } } \)

Answer 2.
Ωm

Answer 3.
(d)All the above

Answer 4.
E = hυ = bc/λ
\(P=\frac { h }{ \lambda } =\frac { h\upsilon }{ c } \)

Answer 5.
µ_r < 1 or µ_r = 0

Answer 6.

Answer 7.
b. Diverging lens

Answer 8.
a. If E is not normal, there is a component a long the tangent to the surface. Then free charge on the surface experience force and will move. But E should have no tangential component in static situation.
OR
V is constant on the surface, therefore E should be normal.
b. E = 0, V = 10V

Answer 9.
G = 12V, Ig = 2.5×10^-3 A
I = 7.5 A

Putting the low resistance S in parallel with the galvanometer

Answer 10.
a. A
b. C

Answer 11.

a. E_r introduced, capacitance increases i.e,.\(\frac { 1 }{ c\omega } \) will decrease ∴ I₀ will be increase so the brightness will be increased
b. R ↑, I₀ ↓ brightness ↓
resistance cause decrease in I₀ ∴ bright ness will be decreased

Answer 12.
a. Displacement current is current due to time varying electric flax

Answer 13.

b.No change in position intensity halved/reduced

Answer 14.
D₂ on reverse biasing so it does not conduct
D₁ on forward biasing so it conduct
R = 3 + 2.5 = 5.5
V = 10V
I = \(\frac { V }{ R }\) = \(\frac { 10 }{ 5.5 }\) = l.82A

Answer 15.
a. i. Convert energy from one form to an other.
ii. Convert message signal to modulated signal for transmission.
b. X → modulater
Y → Power amplifier

Answer 16.

Answer 17.
E α l

Answer 18.
a. The magnetic flux linked with the rectangular loop PQRS is φ = BA = Blx
According to Faraday’s law, induced emf is

Answer 19.
a. V_L = V_C
X_L = X_C

Answer 20.

Answer 21.

Answer 22.
BE = E_b = ∆mc²
= (Zmp + (A-Z) Mn – M) c²
= (20 x 1.00783 + 20 x 1.00867 – 39.962589) x

Answer 23.

Answer 24.
a. I = ne A V_d……….(1)

Answer 25.

Answer 26.
a. Zener diode
Any change in input voltage results in change in voltage drop across Rs. without any change in voltage across zener diode.
b. When V_i increases, main current increases, I_z increases with no change in load current I_L. So that V₀ = V_z = I_L R_L. When V_i decreases, I_z decreases with no change in I_L.
c. Reverse biasing

Answer 27.

Answer 28.
a. Cylinder
b. S1 and S2 are two narrow slits separated by a distance “d”. They are illuminated by a monochromatic source of wavelength λ . A screen is placed at a distance of D from the slits as shown in the figure

Light waves from S1 and S2 reach the point P. The path difference between these two waves is S2N.

Answer 29.
a. For a hydrogen atom, gives the expression to determine the energies of different energy states. But then this equation requires the radius r of the electron orbit. To calculate r, Bohr’s second postulate about the angular momentum of the electron-the quantization condition is used. The angular momentum L is given by
L = mvr
Bohr’s second postulate of quantization says that the allowed values of angular momentum are integral multiples of h/2π

where n is an integer, r_n is the radius of nth possible orbit and u_n is the speed of moving electron in the nth orbit. The
allowed orbits are numbered 1,2,3………
according to the values of n, which is called the principal quantum number of the orbit.
From the relation between u_n and r_n is

Plus Two Physics Previous Year Question Papers and Answers

Kerala Plus Two Physics Model Question Paper 4

Time: 2 Hours
Cool off time : 15 Minutes

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Your are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.
• 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 and 2 carry 1 score each. Answer both.

Question 1.
Energy in a current carrying coil is stored in the form of

a. Electric field
b. magnetic field
c. dielectric strength
d. heat

Question 2.
Who indirectly determined the mass of the electron by measuring the charge of the electron ?

Answer any six questions from question number 3 to 10. Each question carries 2 scores.

Question 3.
Match the following

Question 4.
A student made a circuit as shown in the figure. S1 and S2 are switches and B is a bulb.

a. He argues that this circuit is equivalent to an AND gate. Do you agree with him? Justify your answer.

b. Write down its truth table.

Question 5.
Using the data given below, state as to which of the given lenses will you prefer to use as
i. an eye-piece and
ii. an objective to construct an astronomical telescope? Give reason for your answer.

Question 6.
Electromagnetic spectrum is an orderly arrangement of electromagnetic radiations in the j ascending or descending order of frequency/wavelength
a. Arrange the following electromagnetic radiations in the ascending order of frequency:
Visible rays, Infrared rays, X-rays, micro-waves.
b. Give one application of infrared and X-rays each.

Question 7.
A magnetic needle made of iron is suspended in a uniform external magnetic field. It experience a torque and the needle starts oscillating

a. Write down the frequency of oscillation of the magnetic needle.

b. If this magnetic needle is heated beyond curie temperature while it is oscillating, then its period.

i. increases
ii. decreases
iii. remains the same
iv. becomes infinity

Question 8.
a. An equilateral glass prism is placed on a horizontal surface. A ray PQ is incident I on it. For minimum deviation:

i. PQ is horizontal
ii. QR is horizontal
iii. RS is horizontal
iv. None of these
b. A thick lens gives coloured images due to

Question 9.
The truth table of a logic gate is given below.

a. Identify the gate.
b. Draw the logic symbol of the gate.

Question 10.
a. State Gauss’ law for magnetism.
b. How this differs from Gauss’ law for electrostatics ?

Answer any five question from question number 11 to 16. Each question carries 3 scores.

Question 11.
a. Which of the following symbol represents a universal gate ?

b. Shown below is an experimental set up with a semiconductor diode

i.identify the experiment
ii.draw the resulting graph.

c. With the help of neat circuit diagram obtain an expression for voltage gain of a transistor amplifier in C-E configuration.

Question 12.
a. The electrical analog of mass is
(i) diode
(ii) capacitance
(iii) inductance
(iv) resistance
b. A 2 m long solenoid having diameter 6 cm and 2000 turns has a secondary of 500 turns wound closely near its mid-point. Calculate the mutual inductance between the two coils.

Question 13.
What is de Broglie hypothesis ?
b. Write the formula for de Broglie wave length.
c. Calculate de Broglie wavelength associated with an electron accelerated by a potential difference of 100 volts. Given mass of the electron = 9.1×10^-31kg, h= 6.634×10^-34 JS,1 eV= 1.6×10^-19J

Question 14.
Albert Einstein, the great physist proposed a clear picture to explain photoelectric effect.
a. Explain Einstein’s photo electric equation.
b. Name the quanta of light.

Question 15.
a. To construct an electronic circuit, you want to select a 470 KΩ resistor with 5% tolerance.Draw a schematic diagram indicating the colour combinations that you will select.
b. As the temperature of a metallic resistor is increased; the product of its resistivity and conductivity ………….
i. Increases
ii. Decreases
iii. Remains constant
iv. May increase or decrease
c. Draw a graph showing the relation between resistivity and temperature of a super conductor.

Question 16.
Earth behaves as a magnet with magnetic poles approximately near the geographic poles.
a. The order of magnitude of earth’s magnetic field in tesla is ….
b. What do you understand by ‘dynamo effect’?
c. Classify the following materials into diamagnetic and paramagnetic.
i. Lead
ii. Magnesium
iii. Tungsten
iv. Copper

Answer any four question from question number 17 to 21. Each question carries 4 scores.

Question 17.
When the magnetic flux associated with a coil changes an emf is induced in the circuit.
a. State Faraday’s law of electromagnetic induction.
b. Mention the physical significance of Lenz’s law with an example.
c. When an electrical appliance is switched off, sparking occurs. Why?

Question 18.
a. Obtain an expression for the number of radioactive nuclei present at any instant in terms of the decay constant and initial number of nuclei.
b. The half life of radioactive radon is 3.8 days. Find the time during which 1/20 of radon sample will remain undecayed.

Question 19.
Electric field lines are a pictorial representation of the electric field around charges.
a. State Gauss’s Law in Electrostatics.
b. Using this law derive an expression for the electric field intensity due to a uniformly charged thin spherical shell at a point.
i. Outside the shell
ii. Inside the shell
c. Suppose that you are in a cave deep within the earth. Are you safe from thunder and lightning ? Why ?

Question 20.
a. State Kirchhoff’s rules for the analysis of electrical circuits.

b. The circuit diagram of a potentiometer for the determination of internal resistance of a cell is shown below. Calculate the value of the internal resistance (r) of the cell.
Given R = 100 Ω, balancing length when key (K) open = 60 cm. Balancing length when key (K) closed = 58 cm.

Question 21.
We are familiar with the semiconductors Silicon and Germanium,
a. With a necessary schematic diagram, briefly explain the characteristics of an intrinsic semiconductor.
b. Draw the energy bands of a n-type semi-conductor.
c. The following figure represents a……..

Answer any three quest on from question number 22 to 25. Each question carries 5 scores.

Question 22.
Capacitor is an arrangement to increase the charge carrying capacity of a conductor
a. Each plate of a parallel plate capacitor has a charge q on it. The capacitor is now connected to a battery. Pick out the correct statement/statements.
i. The facing surfaces of the plates have equal and opposite charges.
ii. The battery supplies equal and opposite charges to the two plates.
iii. The two plates of the capacitor have equal and opposite charges.
b. The plates of a parallel plate capacitor each of area A is charged with charges +Q and -Q. Deduce the force acting between the plates of the capacitor.
c. Van de Graaff generator is a high voltage generator used to accelerate charged particles.
Draw a labelled schematic diagram of a Van De Graaff generator and state the principle behind its working.

Question 23.
Force acting on a charged particle when it moves in a combined electric and magnetic field is known as Lorentz force.
a. A charged particle is released from rest in a region of steady and uniform electric and magnetic fields; which are parallel to each other. What will be the nature of the path followed by the charged particle? Explain your answer.
b. A rectangular loop carrying a steady current is placed in a uniform magnetic field. Obtain the expression for the torque acting on the loop.

Question 24.
In the potentiometer circuit shown, the balance point is at X.

State with reason, where the balance point will be shifted, when
a. Resistance R is increased, keeping all parameters unchanged.
b. Resistance S is increased, keeping R constant.
c. Cell P is replaced by another cell whose e.m.f. is lower than that of cell Q.
d. You are asked to compare the emf of two cells using a potentiometer. Draw the circuit diagram for this and explain how you will determine the ratio of e.m.f.

Question 25.
In the figure PQ is a ray incident on a prism ABC.

a. Complete the ray diagram showing the passage of light. Mark angle of incidence i, angle of emergence e, angle of deviation δ and angle of refractions r1 and r2.
b. Using the diagram obtain the relation
δ = i + e – A.
c. The critical angle for diamond is 30°. What is its refractive index?

Answers

Answer 1.
b

Answer 2.
Thomson

Answer 3.

Answer 4.
a. No. It is an OR gate
b.

Answer 5.
i. For an eye piece we prefer convex lens of max power and min.aperture is lens L₄.
ii. Objective must have minimum power and maximum aperture, ie., lens L₁

Answer 6.
a. Microwaves, infrared, visible, x-rays
b. Infrared – Mobile phone (Bluetooth), TV, Video recorders.
X-ray – Detect the fracture of bones.

Answer 7.

b. increases

Answer 8.
a. QR is horizontal
b. disperson.

Answer 9.
a. NOR gate.

Answer 10.
a. Gauss’s law for magnetism states that the net magnetic flux through any closed surface is zero, i.e.,

b. Gauss’s law in electrostatics states that the total flux through a closed surface is 1/ε₀ times the net charge enclosed by the closed surface.

Answer 11.
a. (ii)

b. (i) For studying the V-I characteristics of a p-n junction diode.

Answer 12.
a. (iii) inductance

Answer 13.
a. He proposed that material particles in motion should display wave-like properties.

Answer 14.
a. Einstein explained photoelectric effect based on quantum theory. According to quantum theory, light contain photons having energy hυ, when a photon of energy hυ₀ incident on a metal surface, electrons are liberated. A small portion of the photon energy is used for work function (φ) and remaining energy is appeared as K.E of the electrons.
By law of conservation of energy, we can write hυ = hυ₀ + ½ mv²; hυ energy of incident wave ; hυ₀ -» work function ½mv² -» K.E of electron
b. Photon.

Answer 15.

Answer 16.
a. 10^-5 T or 0.38 x 10^-4 T
b. Earth magnetic field arises due to electrical currents produced by convective motion of metallic fluids in the outer core of the earth. This is called dynamo effect.
c. Lead, Copper – Dia magnetic
Magnesium, Tungsten – Para magnetic

Answer 17.
a. Faraday’s first law: According to first law an EMF is induced in a circuit.when the magnetic flux linked with it changes.
b. Lenz’s law verifies conservation of energy in the electromagnetic induction phenomenon.
When N-pole of a bar magnet is moved towards a coil, the direction of induced current in the coil will be such that the end 2 will behave as N-pole (to oppose the incoming N-pole). For this the current in the coil will be anticlockwise as seen from the right face of the coil (using right hand thumb rule).
c. Due to back emf.

Answer 18.

t = 3.8 x 4.33 = 16.45 days

Answer 19.
a. Gauss’s Law states that the total flux through a closed surface is 1/ε₀ times the net charge enclosed by the closed surface.
b. (i).Outside the sphere (r > R)

c. Yes. This is because the electric field inside the cave will be zero. This is called electrostatic shielding.

Answer 20.
a. First law: The total current entering the junction is equal to the total current leaving the junction.
Second law: Total emf in a closed circuit is equal to the sum of the voltage drops.

Answer 21.

A pure semiconductor which is free from any impurity is called intrinsic semiconductor. Its conductivity controlled by the number of valence electron present in valence band. At 0K no electron is available in the conduction band semiconductor act as insulator.

c. Diode.

Answer 22.
a. i. True ii. True iii. True

c. The high electric field at the pointed ends of comb C1, ionises the air near them. The +ve charges in air are repelled and got deposited on the belt through a corona discharge.

The charges are carried upto C2. A similar corona discharge takes place at C2 and the charges are finally transferred to the shell M. The charges spread over uniformly on the outer surface of M raising its potential to few million volts.

Answer 23.
a. The charged particle execute an accelerated straight line motion along the direction of electric field. Since the electric field and magnetic field are parallel the magnetic field will be in the direction of the motion of the charged particle and hence the force due to magnetic field will be zero.,
b. A rectangular loop carrying a steady current I and placed in a uniform magnetic field experiences a torque. It does not experience a net force.
Consider a rectangular coil ABCD, placed in a uniform magnetic field, B. Then,
τ = I ab B = NIAB sin θ or τ =M x B ,
where A is the area of the coil, N is the no of turns. Here M = I (NA) is called magnetic dipole moment. If θ = 0 or 180, τ = 0.

Answer 24.
a. Balance point will be shifted towards B.
b. No change.
c. Balance point not found on AB.

Potential difference between two points of a current carrying conductor is directly proportional to the length of the wire between the two points.
A battery (B1), Rheostat and key are connected in between A and B. This circuit is called primary circuit. Positive end of E1 and E2, are connected to A and other ends are connected to a two way key. Jockey is connected to a two key through galvanometer. This circuit is called secondary circuit.
Key in primary circuit is closed and then E1 is put into the circuit and balancing length I1 is found out.

Answer 25.

Plus Two Physics Previous Year Question Papers and Answers

Kerala Plus Two Physics Model Question Paper 3

Time: 2 Hours
Cool off time : 15 Minutes

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Your are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.
• 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 – 7 carry 1 score each. Answer any six questions.

Question 1.
Potentiometer measures potential more accurately because

a. It measures potential in the open circuit
b. It uses sensitive galvanometer for null deflection
c. It uses high resistance potentiometer wire
d. It measures potential in the closed circuit

Question 2.
Tesla is the unit of

Question 3.
Write the time constant of C-R circuit ?

Question 4.
Green-house effect is the heating up of earth atmosphere due to____
a. green plants
b.infra-red rays
c. x-rays
d. ultraviolet rays

Question 5.
Rainbow is formed due to a combination of

a. dispersion and total internal reflection
b. refraction and absorption
c. dispersion and focusing
d. refraction and scattering

Question 6.
Ratio of intensities of two waves are given by 4:1. Then find the ratio of the amplitudes of the two waves.

Question 7.
The spectrum obtained from a sodium vapor lamp is an example of

a. band spectrum
b. continuous spectrum
c. emission spectrum
d. absorption spectrum

Questions 8 to 15 carry 2 score each. Answer any 7 questions.

Question 8.
Copper is one of the suitable materials to make connecting wires due to its low resistivity.
a. What do you mean by resistivity?
b. A copper wire is in the form of a cylinder and has a resistance R. It is stretched till its thickness reduces by half of its initial size. Find its new resistance in terms of R.

Question 9.
It was james Clark Maxwell who modified Ampere’s circuital theorem by introducing the concept of displacement current.

a. What do you mean by displacement current?

Question 10.
Match the following

Question 11.
A body of mass m is charged negatively. State whether the following statements are true or false.
a. During charging, there is change in mass of the body.
b. The body can be charged to 2.5 e where e is the charge of an electron.
c. While charging the body by induction new charges are created in it.
d. The force between two charged object is less when there is a medium between them (than in vacuum).

Question 12.
a. A receiver in a communication system must have
i. pick-up antenna
ii. demodulator
iii. amplifier
iv. all of these
b. Which of the following statements is wrong?
i. The attenuation of surface waves in creases with increase in frequency.
ii. The phenomenon involved in sky wave propagation is similar to total internal reflection.
iii. Space wave mode of propagation is used in satellite communication.
iv. Sky wave propagation is useful only in the range of frequencies 30 MHz to 40 MHz.

Question 13.
a. The core of a transformer has the following properties :
i. core is laminated.
ii. hysterisis loop is narrow.
Explain the significance of each property.
b. What is meant by resonance in an LCR circuit ?

Question 14.
a. Permanent magnets should have
i. high retentivity and low coercivity.
ii. low retentivity and high coercivity.
iii. high retentivity and high coercivity.
iv. low retentivity and low coercivity.
b. Distinguish between Para, Ferro an Dia magnetism.

Question 15.

a. From the above figures which one corresponds to a typical semiconductor.
b. Dimension of temperature coefficient α is……..

Questions 16 to 22 carry 3 score each. Answer any 6 questions.

Question 16.
a. Work function of a metal is the
i. energy required by an electron to get absorbed in the metal surface.
ii. minimum energy required by an electron to escape from the metal surface.
iii. energy required by an electron to be retained in the metal surface.
iv. maximum energy required by an electron to escape from the metal surface.
b. Write Einstein’s Photo-Electric Equation and explain the terms in it.
c. All Photo electrons are not emitted with the same energy as the incident photons. Why?

Question 17.
Kirchhoff’s rules are very useful for analysis of electrical circuits.
a. State Kirchhoff s junction rule.
b. Find the effective resistance of the circuit given below :

Question 18.
A fascinating behaviour of the series RLC circuit is the phenomenon of resonance.
a. Explain Resonance in an LCR circuit.
b. Draw a graphical representation of variation of current amplitude in i_m with frequency to ω
c. What do you mean by sharpness of resonance? Explain it.

Question 19.
a. When a low flying aircraft passes over head, we sometimes notice a slight shaking of the picture on our TV screen. Identify the optical phenomenon behind it.
b. In electromagnetic spectra, the wave length and frequencies are inversely related. A radio can tune into any station in the 7.5 MHz to 12 MHz band. Determine the corresponding wavelength band

Question 20.
Various propagation modes are used in communication.
a. Mention two communication system that uses space wave propagation.
b. Why modulation is necessary in communication ?
c. If a signal of frequency cos is used to ω_s modulate a carrier wave of frequency ω_c
which are the frequencies contained in the modulated signal other than ω_c?

Question 21.
Match the following quantities using the analogy between mechanical and electrical quantities.

Question 22.
In a nuclear reactor the chain reaction is carried out under controlled conditions.
a. Name the material that is used as control rods in a nuclear reactor.
b. Average energy of a neutron produced in fission of ₉₂²³⁵U nucleus is…….
c. Write down the reactions involved in the conversion of to ₉₂²³⁸U to ₉₄²³⁹Pu in a nuclear reactor

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

Question 23.
To emit a free electron from a metal surface a minimum amount of energy must be supplied.
a. This energy is called….
b. State three methods to supply this energy to the free electron.
c. When light of frequency 7.21×10¹⁴ Hz is incident on a metal surface, the maximum speed of the ejected electrons is 6×105 m/s. Calculate the threshold frequency for the metal.

Question 24.
Seema constructed a series LCR circuit in the laboratory as shown in the diagram. She found that the voltages across the inductor and capacitor are equal when the circuit is connected to an ac source.


a. State the condition at which the voltages across L and C become equal.

b. Obtain an expression for the frequency at which this situation occurs in a series LCR circuit.

c. Find the voltmeter and ammeter readings in the circuit.

Question 25.
Brewster’s law gives a relationship between angle of polarisation and refractive index of the material.

a. State Brsewster’s law

b. A ray of light is allowed to incident on the surface of a glass plate and it is found that the reflected and refracted rays are mutually perpendicular as shown in the figure. The refracted ray is deviated from its initial path by an angle of 30°
Determine the refractive index of the glass plate.

Question 26.
a. A ray of light travels from a denser to a rarer medium then, the ray
i. doesn’t bend at all.
ii. bends towards the normal.
iii. bends away from the normal.
iv. goes along the normal.
b. Draw a diagram showing the path of a monochromatic light through a triangular prism.
c. Using this diagram obtain the relation

Questions from 27 – 29 carry 5 scores. Answer any 2 questions.

Question 27.
a. What do you mean by barrier potential of a diode ?
b. With the help of a diagram explain the working of a full wave rectifier.

Question 28.
Various phenomena exhibited by light can be explained using the wave theory of light.
a. Name the phenomenon which proves the transverse nature of light.
b. What are the differences between interference and diffraction?
c. A plane wave front is incident on a single slit. Discuss the diffraction pattern formed by the slit. Represent the variation of intensity graphically.

Question 29.
A moving charge can produce a magnetic field.
a. How does a current loop behaves like a magnetic dipole ?
b. Draw the magnetic field lines for a current loop to support your answer.
c. i. What is a cyclotron ?
ii. Write down the expression for cyclotron frequency.

Answers

Answer 1.
a

Answer 2.
magnetic field

Answer 3.
CR

Answer 4.
b

Answer 5.
a

Answer 6.

Answer 7.
c

Answer 8.
a. Resistivity of the material of a conductor is defined as the resistance of the conductor of unit length and of unit area of cross-section.

Answer 9.
a. Displacement current is that current which comes into existence, in addition to the conduction current whenever the electric flux changes with time.
b. Ampere

Answer 10.

Answer 11.
a. true
b. false
c. false
d. true

Answer 12.
a. (iv) all of these
b. (iv) Sky wave propagation is useful only in the range of frequencies 30 to 40MHz

Answer 13.
a. (i) For reducing eddy current. Eddy current heats the core and energy will be lost.
(ii) For reducing hysterisis loss.
b. In LCR, at a particular frequency X_L = X_C. This condition is called resonance. This frequency is called resonance frequency.

Answer 14.
a. iii. high retentivity and high coercivity.
b. Paramagnetism: Feebly magnetise along applied field.
Diamagnetism: Feebly magnetise opposite to magnetic field.
Ferromag netism: Strongly magnetise along magnetic field.

Answer 15.
a. Fig.(2)
b. α = coefficient of temp

Answer 16.
a. ii. minimum energy required by an electron to escape from the metal surface.

c. All the photoelectrons emitted from the metal do not have the same energy. Photoelectric current is zero when the stopping potential is sufficient to repel | even the most energetic photoelectrons, with the maximum kinetic energy (K_max),So that K_{max = eV0}

Answer 17.
a. In an electric circuit, the sum of currents | entering the junction is equal to the sum of currents leaving the junction.
b. Here 3Ω, 6Ω are parallel and 6Ω and 12Ω are parallel.

Answer 18.
a. In LCR, at a particular frequency X_L = X_C. This frequency is called resonance frequency.

c. Sharpness of resonance is depends of quality factor or Q factor.
Q factor is equal to the ratio inductive reactance or capacitative reactance to the impedence at resonance.

Answer 19.
a. Interference

Answer 20.
a. TV Broadcast, Satellite, FM, RADAR,
b. 1. Size of the antenna: We need an antenna having a size comparable to the wave length of the signal.
2. Effective power radiated by antenna,

Answer 21.

Answer 22.

Answer 23.
a. Work function.
b. Thermionic emission, field emission and photo electric emission.

Answer 24.
a. p.d across L and C are equal when inductive reactance = Capacitive reactance (X_L = X_C), i.e., at resonance.
b. At resonance, X_L = X_C

Answer 25.
a. Tangent of angle of polarization is equal to the reflective index.
b. i + r = 90°
θ + r = 90°
θ = 90° – r = 90 – 30 = 60°
n = tan 60° = √3 = 1.732

Answer 26.
a. iii bends away from the normal
b.

Answer 27.
a. During the formation of a p-n junction, holes diffuse from p to n side and electrons diffuse from n to p side. Thus there is excess of positively charged ions in n side and negatively charged ions in p side. This sets up a potential difference across the junction which is called barrier potential. It stops further diffusion.

• During +ve half cycle of a.c, the end A is positive and end B is negative with respect to the centre tap. Diode D1 gets forward biased and conducts current while D2 is reverse biased and does not conduct.
• During -ve half cycle, the end Abe comes negative and end B becomes positive with respect to the centre tap. The diode D gets reverse biased and does not conduct. The diode D2 gets forward biased and conducts current.
• The output current is unidirectional and pulsating which may be filtered by connecting a capacitor parallel to load R_L.

Answer 28.
a. polarization
b.

Answer 29.
a. One face north and other face south.
i.e.,


Cyclotron uses the fact that the frequency of revolution of the charged particle in a magnetic field is independent of its energy. The particles move most of the time inside two semicircular disc-like metal containers, D1 and D2, which are called dees.
The whole assembly is evacuated to minimise collisions between the ions and the air molecules. A high frequency alternating voltage is applied to the dees. Positive ions or positively charged particles (e.g., proton) are released at the centre P. They move a semi-circular path in one of the dees and arrive in the gap between the dees in a time interval T/2; where T, the period of revolution, is given T = 1/ u_c = 2πm/qB
u_c = qB / 2πm. This frequency is called the cyclotron frequency for obvious reasons and is denoted by u_c.

Plus Two Physics Previous Year Question Papers and Answers

Kerala Plus Two Physics Model Question Paper 2

Time: 2 Hours
Cool off time : 15 Minutes

General Instructions to candidates:

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
• Your are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.
• 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 and 2 carry 1 score each. Answer both.

Question 1.
Electromagnets are made of soft iron because soft iron has

a. low retentivity and high coercive force
b. high retentivity and high coercive force
c. low retentivity and low coercive force
d. high retentivity and low coercive force

Question 2.
Draw the symbol of NOR gate

Answer any six questions from question number 3 to 10. Each question carries 2 scores.

Question 3.
a. The electric field of a plane electromagnetic wave traveling in the +ve Z-direction is described by
a. E_x = E₀ sin (kz + ωt)
b. E_x = E₀ sin (kz – ωt)
c. E_x = E₀ sin (2kz)
d. E_x = E₀ sin (kz)
b. We feel excessive sweating on a cloudy day. Why ?

Question 4.
For many purposes, it is necessary to change an alternating voltage from one value to another. This is done with a transformer.
a. The basic principle behind a transformer is…..
b. Give an expression for the voltage and current in a transformer.

Question 5.
a. Name the physical quantity which has its unit joule coulomb^-1. Is it a vector or a scalar?
b. Two plane sheets of charge densities +σ and -σ are kept in air as shown in figure. What are the electric field intensities at point A and B?

Question 6.
Name the electromagnetic waves used for the following applications.
a. Imaging of bones in human body.
b. Mobile phone communication.
c. Remote control of T.V.sets.
d. For sterilizing surgical instruments.

Question 7.
a. Range of an electronic communication system is the
i. distance to the nearest TV station.
ii. distance to the nearest radio station.
iii. largest distance the signal can travel.
iv. largest distance between a source and destination up to which the signal is received with sufficient strength.
b. If the height of TV transmitting antenna is increased its coverage increases. Why?

Question 8.
Match the following in 3 columns.

Question 9.
a. The resistance ‘R’ of a conductor depends on its length ‘I’, area of cross- section ‘A’ and the resistivity of the material ‘ρ’. The correct expression connecting R, I, A and ‘ρ’ is

b. The voltage – current graphs for two resistors of the same material and same radii with lengths L1 and L2 are shown in the figure. If L1 > L2 state with reason, which of these graphs represents voltage current charge for L1?

Question 10.
De Broglie proposed the wave nature of electrons suggesting matter waves.
Find the momentum, speed and de Broglie wavelength of an electron with kinetic energy of 120 eV.

Answer any five questions from question number 11 to 16. Each question carries 3 scores.

Question 11.
a. The work function of a metal is 6 eV. If two photons each having energy 4 eV strike with the metal surface
i. will the emission be possible ?
ii. why ?
b. The waves associated with matter is called matter waves. Let λ_e and λ_p be the de- Broglie wave lengths associated with electron and proton respectively. If they are accelerated by same potential, then

Question 12.
The region around a charge where its effect can be felt is called the electric field.
a. The electric field lines corresponding to an electric field is shown below.

b. Some equipotential surfaces are shown in the figure. What can you say about the magnitude and direction of the electric field ?

Question 13.
Given below is the graph between frequency (υ) of the incident light and maximum kinetic energy (E_k) of emitted photoelectrons.

a. Define the terms – work functions and threshold frequency.
b. Find the values of
i. threshold frequency and
ii.work function from the graph

Question 14.
Consider the logic circuit using NOR gates given below:

a. Write the truth table for the circuit.
b. Identify the logic operation which this circuit is performing.

Question 15.
The phenomenon in which electric current is generated by varying magnetic field is called electromagnetic induction.
a. Which law helps to detect the direction of induced current? State the law.
b. Explain what are eddy currents.
c. Write any two uses of eddy currents.

Question 16.
Biasing is provided for maintaining proper current flow across a p-n junction.

a. In a biased p-n junction the net flow of holes is from ‘n’ region to ‘p’ regional


b. For the device shown below draw the V-I characteristics when the potential is applied between the terminals A and B.

Answer any four questions from question number 17 to 21. Each question carries 4 scores.

Question 17.
a. Find the equivalent resistance of the circuit.

b. Determine the current through the 75Ω resistance.

Question 18.
a. A convex lens
i. is thicker at the edges than at the middle.
ii. is thicker at the middle than at the edges.
iii. diverges rays of light.
iv. is of uniform thickness everywhere.
b. With the help of a ray diagram sketch the image formation of a convex lens when the object is between C and F.
c. Derive the lens maker’s formula.

Question 19.
Remya makes the following circuit to measure the emf of a cell.

She says that the voltmeter reading will give the emf of the cell.

a. The Physics teacher says that it is not :possible to measure the emf of the cell in this way. Justify this statement.
b. Explain with a circuit diagram the method to measure the emf of a cell with a potentiometer if you are given another standard cell, (whose e.m.f. is known)

Question 20.
a. What do you mean by Q value of a nuclear reaction?
b. Write down the expression for Q value in the case of α decay.
c. Two nuclei have mass numbers in the ratio 1 : 64. What is the ratio of their nuclear radii ?

Question 21.
A capacitor is a device used for storing charge as well as energy. It is based on a property called capacitance.
a. Write the SI unit of capacitance and define it.
b. You are given two capacitors of 2µF and 3µF. What are the maximum and minimum values of capacitance that can be obtained by combining them?
c. Obtain an expression for the electrostatic energy stored in a capacitor.

Answer any three questions from question number 22 to 25. Each question carries 5 scores.

Question 22.
To emit a free electron from a metal surface a minimum amount of energy must be supplied.
a. This energy is called …….
b. State three methods to supply this energy to the free electron.
c. When light of frequency 7.21×10¹⁴ Hz is incident on a metal surface, the maximum speed of the ejected electrons is 6×10⁵ m/ s. Calculate the threshold frequency for the metal.

Question 23.
Figure shows a graph between angle of incidence and the respective deviation of light when it is passed through an optical element.

a. Name this optical element.
b. What will happen to the angle of minimum deviation D if it is completely immersed in water? Justify your answer.
c. Obtain an expression for the refractive index of the material of this optical element.

Question 24.
The idea of ‘Electric field lines ’ is useful in pictorially mapping the electric field around charges.
a. Give any two properties of electric lines of force.
b. State Gauss’s theorem in electrostatics.
c. Using the theorem, derive an expression for electric field due to a uniformly charged spherical shell.
i. at a point outside the shell
ii. at a point inside the shell
d.

A point charge of +10 μc is at a distance of 5cm directly above the centre of a square of side 10 cm as shown in the figure. What is the electric flux through the square?

Question 25.
Gauss’s law can be used to determine the electric field due to a charge distribution, a. Below are some statements about Gauss’s law. Say whether they are true or false.
i. Gauss’s law is valid only for symmetrical charge distributions.
ii. The electric field calculated by Gauss’s law is the field due to charges inside the Gaussian surface.
b. Apply Gauss’s law to find the electric field due to an infinitely long plane sheet of charge.
c. “There can be no net charge in a region in which the electric field is uniform at all points”. Do you agree with this statement? Justify your answer.

Answers

Answer 1.
d

Answer 2.

Answer 3.
a. b. E_x = E₀ sin (kz – ωt)
b. The clouds prevents IR radiation from passing through and thus keeps the earth’s surface warm.

Answer 4.
a. Mutual induction

Answer 5.
a. Electric potential. It is a scalar quantity.

Answer 6.
a. x-rays
b. Radio waves
c. Infrared rays
d. Ultraviolet rays

Answer 7.
a. iv. largest distance between a source and destination up to which the signal is received with sufficient strength.
b. We know range, d = √2hR ; Where h is the height of the antenna. Therefore increasing height increases the range ie., coverage.

Answer 8.

Answer 9.
a. \(R=\frac { pl }{ A }\)
b. B represents voltage change for L. Resistance of B is greater than that for A, since resistance increases with length.

Answer 10.
De Broglie wavelength of electrons

from V², we can calculate V so we get the value of P also.

Answer 11.
a. (i) No
(ii) Free electrons are bound to the metal with some force. The minimum energy j required to liberate an electron from the metal is called work function, here the energy of one photon is less than work function. So emission will not be possible.
b. (i) λ_e > λ_p

Answer 12.
a. E_A = E_C > E_B
b. The direction of electric field at any point on the equatorial line of the dipole will be opposite to the dipole moment. The magnitudes of electric fields are equal

Answer 13.
a. Work functions: It is the minimum amount of energy required by an electron to just escape from the metal surface of the metal.
Threshold frequency: The minimum value of the frequency of incident radiation which can emit photo electrons from a material.
b. i.Threshold frequency,v₀ = 10 x 10¹⁴ Hz
ii. Work function = hv₀
= 6.63 x 10^-34 x 10 x 10¹⁴
= 6.63 x 10^-19 J

Answer 14.
a. Truth Table

Answer 15.
a. Lenz’s law. This law states that the direction of the induced e.m.f or current is such as to oppose the cause that produced it
b. The currents induced in the body of a conductor, when the magnetic flux linked with the conductor changes are called eddy currents or Focault’s currents
c. i. Electric Brakes
ii. Speedometer

Answer 16.
a. Reverse

Answer 17.

Answer 18.
a. ii. is thicker at the middle than at the edges.

Answer 19.
a. The voltmeter reads terminal potential difference. Emf cannot be measured in this way since the cell is connected to a resistance. Emf is the potential different across the terminals of a cell in a open circuit.

Answer 20.
a. The disintegration energy or the Q- value of a nuclear reaction is the difference between the initial mass energy and the total mass energy of the decay products.
b. For α -decay

Answer 21.
a. SI unit of capacitance is farad. Capacity of a conductor is said to be one farad if one coulomb of charge on it raises its potential by one volt.
b. If the capacitors are in series,

Answer 22.
a. Work function.
b. Thermionic emission, field emission and photo electric emission.
c. u = 7.21 x 10¹⁴ Hz, V = 6 x 10⁵ m/s

Answer 23.
a. Prism
b. The angle of minimum deviation decreases.
Refractive index of glass with respect to water is 1.5. But refractive index of glass with respect to water is 1.33.

c.

Answer 24.
a. i. Electric lines of force will never intersect.
ii.The tangent to the line of force at any point gives the direction of electric field at that point.
b. The electric flux through any closed surface in free is equal to 1/ε₀ times the total charge enclosed by the surface.

Answer 25.
a. i. False
ii. False

c. Yes, there can be no net charge in a region in which the electric field is uniform at all points. Consider a region with uniform electric field and a cubical gaussian surface in it whose face is perpendicular to electric field. Now from one face electric field enters which is considered to be +ve from the possible face it gets out which is considered to be -ve. So net flux through the gaussian surface is zero.

Plus Two Physics Previous Year Question Papers and Answers

Kerala State Board New Syllabus Plus Two Physics Previous Year Question Papers and Answers.

Kerala Plus Two Physics Model Question Paper 1 with Answers

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

General Instructions to candidates:

• There is a ‘cool off-time’ of 15 minutes in addition to the writing time of 2 hrs.
• You are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and the only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.
• 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 – 7 Carry 1 Score each. Answer any six questions. (6 × 1 = 6)

Question 1.
Write the expression for intensity of electric field near to the surface of a charged conductor with uniform charge density σ.
Answer:
E = \(\frac{\sigma}{\varepsilon_{0}}\)

Question 2.
The unit of electrical resistivity is ……….
Answer:
Ωm (ohm meter)

Question 3.
E.m.f can be induced in a coil placed in an external magnetic field by:
a) Changing the intensity of the magnetic field
b) Changing the area of the coil
c) Changing the orientation of the coil
d) All of the above
Answer:
d) All of the above

Question 4.
Write the energy and momentum associated with a moving photon.
Answer:
E = hν, P = mc

Question 5.
The value of relative permeability of a diamagnetic material is;
a) μ_r > 1
b) μ_r = 1
c) μ_r < 1
d) μ_r = 1
Answer:
c) μ_r < 1

Question 6.
The electric field amplitude of an electromagnetic wave is 15V/m. Find the magnetic field amplitude of the wave.
Answer:
B = \(\frac{E}{C}=\frac{15}{3 \times 10^{8}}\) = 5 × 10^-8T

Question 7.
A convex lens is placed in a medium having a refractive index greater than that of the lens. The lens now behaves as;
a) Converging lens
b) Diverging lens
c) Plane glass plate
d) None of the above
Answer:
b) Diverging lens

Questions 8 to 15 carry 2 scores each. Answer any 7 questions. (7 × 2 = 14)

Question 8.
a) ‘Electrostatic field is always normal to the surface of a charged conductor’. Justify the statement.
b) The value of elelctric potential at the surface of a charged conductor is 10V. Find the value of the intensity of the electric field and potential at a point interior to it.
Answer:
a) The surface of the charged conductor is an equipotential surface. In equipotential surface, the potential is the same and hence the electric field is always normal to the surface of a charged conductor.
b) E = 0

Question 9.
A galvanometer with a coil of resistance 12Ω shows a full-scale deflection for a current of 2.5 mA. How can it be converted into an ammeter of range 7.5 A?
Answer:
G= 12Ω, I_g= 2.5 mA = 2.5 × 10^-3A, I = 7.5 A
S = \(\frac{I_{g} \times G}{I-I_{g}}=\frac{2.5 \times 10^{-3} \times 12}{7.5-2.5 \times 10^{-3}}=4 \times 10^{-3} \Omega\)

Question 10.
The curves shown in figure are drawn for different magnetic materials. Among the three curves, name the curve that,

a) Represent the material usually used for making permanent magnets.
b) Represent the material usually used for making electromagnets.
Answer:
a) A
b) C

Question 11.
A capacitor C, a variable resistance R, and a bulb B are connected in series to a.c. mains in the circuit as shown. The bulb glows with some brightness. How the glow of the bulb change if.

a) A dielectric slab is introduced between the plates of the capacitor.
b) The resistance R is increased keeping the same capacitance.
Answer:
a) The brightness of bulb increases.
(When dielectric slab is introduced, capacitance increases hence capacitive reactance decreases, then bulb glows with more brightness.)
b) The brightness of bulb decreases.

Question 12.
James Clerk Maxwell modified Ampere’s circuital theorem by introducing the concept of displacement current.
a) What do you mean by displacement current?
b) Write down the equation for displacement current.
Answer:
a) The current due to time varying electric field is called displacement current.
b) i_d = \(\varepsilon_{0} \frac{\mathrm{d} \varphi}{\mathrm{dt}}\)

Question 13.
An object AB is kept in front of a concave mirror as shown in figure.

a) Complete the ray diagram showing the image formation of object.
b) How will the position and intensity of image be affected if the lower half of the mirror’s reflecting surface is painted black?
Answer:
a)

b) The position of image does not charge. But the intensity decreases.

Question 14.
Assuming that the two diodes D₁ and D₂ used in the electric circuit as shown in figure are ideal. Find out the value of current flowing through 2.5Ω resistor.

Answer:
Since D₂ is reverse biased, no current flows through 3Ω. We need to consider only the other two resistance 3Ω and 2.5Ω, which are connected in series. Total resistance, R = 3Ω + 2.5Ω = 5.5Ω
v = 10V
I = \(\frac{V}{R}=\frac{10}{5.5}\) = 1.81 A

Question 15.
a) Mention the function of the following used in the communication system
(i) Transducer
(ii) Transmitter
b) Figure shows the block diagram of an AM transmitter. Identify boxes X and Y.

Answer:
a) i) Transducer: The device that converts one form of energy into another is called transducer.
ii) Transmitter – Atransmittertransmits the information

b) x → Modulator
y → Power Amplifier

Questions 16 to 22 carry 3 scores each. Answer any 6 questions. (6 × 3 = 18)

Question 16.
Three capacitors of capacitances 2µF, 3µF and 4µF are connected in series.
a) Find the equivalent capacitance of the combination
b) The plates of a parallel plate capacitor have an area 20 cm² each are separated by a distance of 2.5 mm. The capacitor is charged by connecting it to a 400V supply. How much electrostatic energy is stored in the capacitor?
Answer:
a) C₁ = 2μF = 2 × 10^-6F
C₂ = 3μF = 3 × 10^-6F

b) A = 20cm² = 20 × 10^-4m²
d = 2.5 mm = 2.5 × 10^-3m
ε₀ = 8.85 × 10^-12C²/Nm²
v = 400v

Question 17.
A circuit using a potentiometer and a battery of negligible internal resistance is set up as shown to develop a constant potential gradient along the wire PQ. Two cells of e.m.fs E₁ and E₂ are connected in series as in figure in combination 1 and 2. The balance points are obtained respectively at 400 cm and 240 cm from point P. Find

a) The ratio between E₁ and E₂
b) Balancing length for the cell with emf E₁ only.
Answer:
a) From the connection (1), we get
E₁ + E₂ = k × 400 ………(1)
k = constant
From the connection (2), we get
E₂ – E₁ = 240 K ……….(2)
Adding (1) and (2), we get
2E₂ = 640 K
E₂ = 320 K
Subtituting for E₂ in equation (1)
E₁ + 320 K = 400 K
E₁ = 80 K
The ratio \(\frac{E_{1}}{E_{2}}=\frac{1}{4}\)
b) l₁ be the balancing length of E₁
E₁ = kl₁
80k ∝ kl₁
l₁ = 80 cm

Question 18.
A conducting rod PQ of length ‘l’ connected to a resistance ‘R’ is moved at a uniform speed ‘V’, normal to a uniform magnetic field ‘B’.

a) Deduce the expression for e.m.f induced in the conductor.
b) Find the magnitude and direction of current through the conductor.
Answer:
a) flux, Φ = BA
Here, Area A = ldx
dx is small displacement rod in time Δ T
Φ = B × l × dx

Question 19.
In tuner circuits, we use the phenomenon of resonance.
a) Write the condition of resonance in a series LCR circuit.
b) A series LCR circuit uses L = 0.1 H, C = 10μF and R = 100Ω. Find the value of frequency at which the amplitude of current is maximum.
Answer:
a) Lω = \(\frac{1}{\mathrm{C} \omega}\)
b) L = 0.1 H, C = 10μF = 10 × 10^-6F

Question 20.
The focal length of a lens has dependent on its radii of curvatures and refractive index. Derive lens maker’s formula.

Question 21.
a) Write the expression for the de Broglie wavelength associated with a charged particle having charge ‘q’ and mass ‘m’, when it is accelerated by a potential of ‘V’ volts.
b) A proton and an electron have the same kinetic energy. Which one has a greater value of de Broglie wavelength and why?
Answer:

For electron, λ_e = \(\frac{h}{\sqrt{2 m_{e} K E_{e}}}\)
But KE_p = KE_e and m_p > M_e, hence λ_e > λ_p
Electron has greater de Broglie wavelength.

Question 22.
Find the binding energy per nucleon of \({ }_{20}^{40} \mathrm{Ca}\) nucleus.
Given m\({ }_{20}^{40} \mathrm{Ca}\) = 39.962589u.
mp = 1.00783u, mn = 1.00867u.
Take 1 amu = 931 MeV/c²
Answer:
Mass detect, Δm = Zm_p + (A – Z) m_n – M
Δm = 20 m_p + 20 m_n – 39.962589
= 20 × 1.00783 + 20 × 1.00867 – 39.962589
= 0.367411 u
Binding energy = 0.367411 × 931 = 342.06 MeV

Questions from 23 – 26 carry 4 scores. Answer any 3 questions. (3 × 4 = 12)

Question 23.
Gauss’s theorem is useful for finding the intensity of elelctric field.
a) Write Gauss’s law in its mathematical form
b) Using the law, prove that the intensity of the electric field at a point due to a uniformly charged infinite plane sheet is independent of the distance from it.
Answer:
\(\phi=\oint \overrightarrow{\mathrm{E}} \cdot \mathrm{d} \overrightarrow{\mathrm{s}}=\frac{\mathrm{q}}{\varepsilon_{0}}\)

Question 24.
a) Express Ohm’s law in terms of current density, electrical resistivity, and intensity of the electric field.
b) Explain the variation of resistance of a semiconductor with temperature. Also, draw the graph showing the variation of resistivity of silicon with temperature.
Answer:
a) J = σE
b) As temperature increases, the number density of electrons (η) of semiconductor increases.
ρ = \(\frac{m}{h e^{2} \tau}\)
Hence resistivity decreases with increase in temperature.

Question 25.
The relation between the magnetic field and current is given by Biot-Savart’s law.
a) Write the expression for the magnetic field at point along the axis of a circuit loop of radius ‘R’ carrying a current ‘I’.
b) From the above expression. Find the value of magnetic field at the centre of the loop.
c) Sketch the magnetic field lines for current carrying circular loop
Answer:
a) B = \(\frac{\mu_{0} \mathrm{NIR}^{2}}{2\left(\mathrm{x}^{2}+\mathrm{R}^{2}\right)^{3 / 2}}\)
I → Current
N → Number of turns
X → distance tot he point from the center of loop
b) B = \(\frac{\mu_{0} N I}{2 a}\)
c)

Question 26.

a) Identify the diode in the circuit and write the use of the resistance Rs.
b) Explain how the diode helps to stabilize the output voltage of the circuit.
c) Name the type of biasing used in this diode
Answer:
a) Zener diode, Voltage regulator
b) Solar Cell: Solar cell is a junction diode used to convert solar energy into electrical energy.

Circuit details:

Its p-region is thin and transparent and is called emitter. The n-region is thick and is called base. The output is taken across R_L.

Working: When light falls on this layer, electrons from the n-region cross to the p-region and holes in the p-region cross into the n-region. Thus a voltage is developed across R_L.
Solar cells are used to charge storage batteries during the daytime.
c) Reverse bias

Questions 27 to 29 carry 5 scores. Answer any 2 questions. (2 x 5 = 10)

Question 27.
In the figure, PQ is the incident ray on the equilateral glass prism ABC.

a) Complete the ray diagram showing the passage of light and mark the angle of deviation.
b) Derive an expression for the refractive index of the material of the prism.
Answer:

b)

ABC is a section of a prism. AB and AC are the refracting faces, BC is the base of the prism. ∠A is the angle of the prism.

A ray PQ incidents on the face AB at an angle i₁. QR is the refracted ray inside the prism, which makes two angles r₁ and r₂ (inside the prism). RS is the emergent ray at angle ‘i₂’

The angle between the emergent ray and incident ray is the deviation ‘d’.
In the quadrilateral AQMR,
∠Q + ∠R = 180°
[since N₁M and NM are normall
i.e. ∠A + ∠M = 18O° ………(1)
In the ΔQMR,
∴ r₁ + r₂ + ∠M = 180°……..(2)
Comparing eq (1) and eq (2)
r₁ + r₂ = ∠A ……….(3)
From the ΔQRT,
(i₁ – r₁) + (i₂ – r₂) = d
[since exterior angle equal sum of the opposite interior angles]
(i₁ + i₂) – (r₁ + r₂) = d
but, r₁ + r₂ = A
∴ (i₁ + i₂) – A = d
(i₁ + i₂) = d + A ……..(4)
It is found that for a particular angle of incidence, the deviation is found to be minimum value ‘D.
At the minimum deviation position,
i₁ = i₂ =i, r₁ = r₂ = r and d=D
Hence eq (3) can be written as,


It is found that when the angle of incidence increases deviation (d) decreases and reaches a minimum value and then increases. This minimum value of the angle of deviation is called the angle of minimum deviation.

Question 28.
According to Christian Huygens’s wave theory, light emanating from a source as wavefronts.
a) What is the shape of wavefront emerging from a linear source?
b) Derive the mathematical expression for the bandwidth of interference bands obtained in young’s double-slit experiment with the help of a suitable diagram.
Answer:
a) Cylinder
b)

S₁ and S₂ are two coherent sources having wavelength A. Let ‘d’ be the distance between two coherent sources. A screen is placed at a distance D from sources. ‘O’ is a point on the screen equidistant from S₁ and S₂.
Hence the path difference, S₁O – S₂O = 0
So at ‘O’ maximum brightness is obtained.
Let ‘P’ be the position of nm bright band at a distance x_n from O. Draw S₁A and S₂B as shown in the figure.
From the right angle ΔS₁AP



This is the width of the bright band. It is the same for the dark band also.

Question 29.
a) The radius of nth stationary orbit of hydrogen atom is:
r_n = \(\frac{\mathrm{n}^{2} \mathrm{~h}^{2} \varepsilon_{0}}{\pi \mathrm{me}^{2}}\)
Using Bohr postulates, obtain an expression for the energy of electron in the stationary states of H-atom.
b) Draw the energy level diagram showing how the spectral lines corresponding to Balmerseries occur due to the transition between the energy levels.
Answer:
a) Consider a hydrogen atom which has one electron revolving around the nucleus having one proton. The centripetal force for an electron is provided by the electrostatic force between electron and proton

b) Energy level diagram of the hydrogen atom

Note: An electron can have any total energy above E = 0 EV. In such situations electron is free. Thus there is a continuum of energy states above E = 0 EV.

Kerala State Board New Syllabus Plus Two Physics Previous Year Question Papers and Answers.

Kerala Plus Two Physics Previous Year Question Paper March 2017 with Answers

Time: 2½ Hours
Cool off time : 15 Minutes

General Instructions to Candidates

• There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2½ hrs.
• You are not allowed to write your answers nor to discuss anything with others during the ‘cool off time’.
• Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
• Read questions carefully before you answering.
• All questions are compulsory and the only internal choice is allowed.
• When you select a question, all the sub-questions must be answered from the same question itself.
• 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.
A concave lens always produces ………….. images
i. real
ii. virtual
iii. magnified
iv. None of these

Question 2.
A Zener diode is always operated in …….. bias.

Question 3.
Momentum of a photon with wavelength λ is……

Question 4.
Write down the truth table of a NOR gate.

Question 5.
a. How many electrons constitute an electric charge of -16 µC?
(i) 10¹³
(ii) 10¹⁴
(iii) 10¹⁵
(iv) 10¹²
b. An electric dipole is a pair of equal and opposite point charges +q and -q separated by a distance r. Write an expression for its dipole moment.
c. When an electric dipole is subjected to a uniform electric field, what will happen?

Question 6.
A message signal of frequency 10kHz and peak voltage 10V is used to modulate a carrier of frequency 1 MHz and peak voltage 20V. Find the modulation index.

Question 7.
a. Resistivity of a conductor depends upon
(i) its material
(ii) its cross-sectional area
(iii) its length
(iv) All of the above
b. Calculate the current flowing through the following circuit :

c. A potentiometer is a device to measure emf of a cell. Explain how the emfs of two cells can be compared using a potentiometer.

Question 8.
a. Choose the wrong option.
(i) Volt = Weber / second
(ii) Weber = Henry x Ampere
(iii) Joule = Henry x Ampere²
(iv) Volt = Weber x Second
b. The current in a coil of self-inductance 0.1 H varies from 2A to 5A in a time of 1ms. Find the induced emf across the coil.

Question 9.
a. Sound waves do not exhibit
i. interference
ii. diffraction
iii. polarization
iv. reflection
b. Describe Young’s double-slit experiment to determine the bandwidth of the interference pattern.
OR
a. The intensity of scattered light I in Rayleigh scattering is proportional to……
b. Explain the diffraction pattern obtained due to a single slit and represent graphically the variation of intensity with angle of diffraction.

Question 10.
a. Define half-life period of a radioactive nucleus. Write down the relation connecting half-life period and mean life.
b. Define 1 amu. Calculate its energy equivalent in MeV.

Question 11.
Photoelectric current does not depend on energy of the radiation, but on its intensity. Explain?

Question 12.
a. Speed of light in glass is 2 x 10⁸ m/s. The Refractive index of glass is……
b. For an equilateral prism made of a material of refractive index √2 . find the angle of minimum deviation for a ray of monochromatic light.
c. Draw the ray diagram of a simple microscope that uses a single convex lens. Derive an expression for its linear magnification.

Question 13.
a. A dielectric slab is placed between the plates of a parallel plate capacitor. Its capacitance
i. becomes zero
ii. remains the same
iii. decreases
iv. increases
b. Derive an expression for energy stored in a capacitor.

Question 14.
a. At resonance, in an LCR circuit, the emf and current are
(i) in phase
(ii) out of phase
(iii) having a phase difference of \(\frac { \pi }{ 2 } \)
(iv) having a phase difference of \(\frac { \pi }{ 6 } \)
b. In the following circuit, find the value of V

OR
a. In a circuit carrying an ideal coil with negligible resistance, the power dissipated is …….
b. In the following circuit, find the impedance.

Question 15.
Explain hysteresis and draw hysteresis curve for a ferromagnetic substance.

Question 16.
Choose the appropriate values for X-rays from the given table.

Question 17.
a. Unit of wavenumber is
i. Hz
ii. eV
iii. m
iv. m^-1
b.Energy of ground state of a hydrogen atom is -13.6 eV. What is its ionization potential?

Question 18.
The current amplification factor for CB configuration of a transistor is 0.9. Find out the current amplification ion factor for CE configuration.

Question 19.
a. An electric charge q is moving with a velocity v in the direction of a magnetic field B. The magnetic force acting on the charge is

b. starting from Biot – Savart law, obtain an expression for the magnetic field at an axial point of a circular coil carrying current.
OR
a. An ammeter is a current measuring device which is always connected in an electric circuit.
b. Describe a cyclotron and obtain an expression for cyclotron frequency.