Plus One Chemistry Model Question Paper 4

Kerala Plus One Chemistry Model Question Paper 4

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

General Instructions to candidates

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

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

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

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

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

Question 4:
What is dry ice?

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

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

Question 7:
Sodium hexametaphosphate is commercially called

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

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

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

Question 10:
Write the IUPAC names of the following.

Question 11:
Consider the reaction given below:

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

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

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

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

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

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

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

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

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

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

Question 20:
Give the structures of the following compounds.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Answers

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

Answer 2:
Law of definite proportions.

Answer 3:

Answer 4:
Solid CO₂

Answer 5:

Answer 6:
Gay Lussac’s law.

Answer 7:
Calgon.

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

Answer 9:

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

Answer 11:

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

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

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

Answer 15:

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

Answer 17:

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

Answer 19:
Sawhorse method.

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

Answer 20:

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

Answer 22:

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

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

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

Answer 25:

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

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

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

Answer 29:

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

∴ Emperical formula of the compound

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

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

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

Answer 33:

Plus One Chemistry Previous Year Question Papers and Answers