Kerala Plus One Chemistry Question Paper June 2022 with Answers

Reviewing Kerala Syllabus Plus One Chemistry Previous Year Question Papers and Answers Pdf June 2022 helps in understanding answer patterns.

Kerala Plus One Chemistry Question Paper June 2022

Time : 2 Hours
Maximum : 60 Scores

Answer any 8 questions from 1 to 11. Each carries 2 scores: (8 × 2 = 16)

Question 1.
(i) Choose the correct set of quantum numbers from the following:
(A) n = 2, l = 0, m = 0, s = +\(\frac{1}{2}\)
(B) n = 2, l = 2, m = -2, s = +\(\frac{1}{2}\)
(C) n = 3, l = 1, m = -2, s = 1
(D) n = 1, l = 1, m = -1, s = –\(\frac{1}{2}\) (1)
Answer:
(A) n = 2, l = 0, m = 0, s = +\(\frac{1}{2}\)

(ii) Sketch the shape of 2s orbital. (1)
Answer:

Question 2.
Calculate the wavelength of an electron moving with a velocity of 10 m/s. (mass of electron = 9.1×10 31 kg) 10 m/s
Answer:
For the de-broglie’s equation
λ = \(\frac{h}{mv}\)
Here m = 9.1 × 10^-31 kg and v = 10 m/s
So, λ = \(\frac{h}{mv}\) = \(\frac{h}{mv}\) = 7.281 × 10^-5 m

Question 3.
With the help of Fajans rules, explain why the ionic compound LiC/exhibit covalent character.
Answer:
Smaller the cation, larger the anion more the covalent character of an ionic bond. So LiCI shows covalent character.

Question 4.
Complete the following table:

Answer:

Question 5.
Consider the following redox reaction:
Zn_(s) + 2HCl_(aq) → ZnCl_2(aq) + H_2(g)
Identify the oxidizing agent and reducing agent in the above reaction.
Answer:

Oxidation occurs to redusing agent – Zn
Reduction occurs to redusing agent – HCl

Question 6.
What is Heavy water? Give any one use of it.
Answer:
Heavy water is Deuterium Oxide (D₂O).
• It is used as moderator in Nuclear reactors.

Question 7.
Match the compounds in Column A with their properties in Column B:

Answer:

Question 8.
Explain the difference in properties of diamond and graphite on the basis of their structures.
Answer:
Diamond

• sp³ hybridisation
• Hardest material due to three dimensional structure
• insulator
• tetra hedral structure

Graphite

• sp² hybridisation
• Slippery in nature
• Due to presence of free electron, it is a conductor of electricity
• hexagonal layers

Question 9.
Write the IUPAC names of the following compounds:
Answer:
i) 2,5,6-Trimethyloctane
ii) hexa-5-one-1-oicacid or 5-Oxohexanoic acid

Question 10.
Distinguish electrophiles from nucleophiles. Give one example for each of them.
Answer:

Electrophile	Nucleophile
Electron loving species	Nucleus loving species
May be neutral or positive	May be neutral or negative
Eg.BF3, Carbonations	Eg. NH3, OH, Cl, Br

Question 11.
What is acid rain? Write any one of its adverse effect to the environment.
Answer:
If the pH of the rain water is less than 5.6. It is is called acid rain.
• Aquatic life is destroyed.
• Harmful for agriculture.

Answer any 8 questions from 12 to 23. Each carries 3 scores. (8 × 3 = 24)

Question 12.
(i) How many significant figures are present in 0.0025? (1)
Answer:
0.0025- 2 significant figure

(ii) State and illustrate the law of multiple proportions. (2)
Answer:
Law of multiple proportion: When two elements combine to form more than one compound the fixed mass of the element combined with the other bear a simple whole no. ratio.

Question 13.
Consider the reaction in which 3g of hydrogen re-acts with 30g of oxygen to form water under suitable conditions.
(i) Find the number of moles of H₂ and O₂ respectively. (1)
No. of moles of H₂ = \(\frac{3}{2}\) = 1.5 mol
ie, \(\frac{\text { given mass }}{\text { molar mass }}\) = no. of mols
No. of moles of O₂ = \(\frac{30}{32}\) = 0.9375 mol

(ii) Identify the limiting reagent and calculate the amount of water produced in the reaction. (2)
Answer:

Question 14.
Which of the following represents the general &uter electronic configuration of group 15 elements? (1)
(a) ns²
(b) ns²np³
(c) ns²np⁴
(d) ns²np⁶
Answer:
(b) ns²np³

(ii) Explain the variation of the atomic radii of elements as we move from top to bottom in a group in the periodic table. Give reason. (2)
Answer:
As we move down the group. Size increases as the no. of shell increases. The size also increases.

Question 15.
(i) Define electronegativity. (1)
Answer:
It is the tendency of an atom to attract the shared pair of electron.

(ii) Name any one scale to express the electronegativity of elements. (1)
Answer:
Mulliken Scale, Pauling scale.

(iii) Which is the most electronegative element in the periodic table? (1)
Answer:
Flourine

Question 16.
Derive ideal gas equation.
Answer:

Question 17.
(i) What is meant by critical temperature of a gas? (1)
Answer:
It is the temperature above which a gas cannot be liquified whatever be the pressure applied.

(ii) Critical temperatures of two gases A & B are 5.3 K and 405.5 K respectively. Which one of this can be liquified easily? Give reason. (2)
Answer:
B can be easily liquified
Higher the critical temperature easier to liquify.

Question 18.
(i) Which of the following is not correct for the isothermal and free expansion of an ideal gas?
(A) W = 0
(B) q = 0
(C) P_ex = 0
(D) ∆U ≠ 0
Answer:
(D) ∆U ≠ 0

(ii) Calculate the amount of work done during the expansion of an ideal gas from 2 litre to 10 litre against a constant external pressure of 1 atm.
Answer:
Work done (W) = -p . ∆V
= -p (V₂ – V₁)
= -1(10-2)
= -8litre – atm
i.e. litre -atm work is done by the system

Question 19.
(i) For a chemical reaction, the reaction quotient (Q_c) is greater than the equilibrium constant (K_c). Predict the direction of reaction. (1)
Answer:
Backward reaction is favoured

(ii) Predict the effect of change in pressure and temperature in the following reaction at equilibrium:

Answer:
High pressure favours forward reaction as the no. of mole decreases in the forward reaction. Low temperature is favoured for forward reaction as the reaction is exothermic.

Question 20.
Balance the following redox reaction in acidic medium:

Answer:
Fe²⁺ + \(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) → F³ + Cr³⁺ acidic medium

Step I : Fe²⁺ → Fe³⁺ oxidation half
\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) → Cr³⁺ Reduction half

Step II: Balancing atoms other than O & H
Fe²⁺ → Fe³⁺
\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) → 2 Cr³⁺

Step III: Balancing O & H by adding H₂O & H⁺
Fe²⁺ → Fe³⁺
\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) + 14 H⁺ → 2 Cr³⁺ + 7H₂O

Step IV: Adding electrons to balance charges
Fe²⁺ → Fe³⁺ + \(\overline{\mathrm{e}}\)
\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) + 14 H⁺ + 6\(\overline{\mathrm{e}}\) → 2 Cr³⁺ + 7H₂O

Step V: Equalising the no. of electrons in both
6Fe²⁺ → 6Fe³⁺ + 6\(\overline{\mathrm{e}}\)
\(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) + 14 H⁺ + 6e → 2 Cr³⁺ + 7H₂O

Step VI: Adding the two half reactions
6Fe²⁺ + \(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) + 14 H⁺ + 6e → 2 Cr³⁺ + 7H₂O
Hence equation is balanced.

Question 21.
Explain the classification of hydrides by citing suit-able examples.
Answer:
Ionic hydrides are hydrides formed by alkali metals and alkaline earth metals, ie. group I and II or s block elements eg. NaH, CaH₂
Molecular Hydrides are hydrides formed by p block elements, eg BH₃, CH₄, NH₃ …
Metallic hydrides are hydrides formed by transition, elements, eg . WH

Question 22.
(i) Which of the following compound does not show cistrans isomerism?
(A) CHCl = CHCl
(B) CH₃CH = CHCH₃
(C) CH₃CCl = CClCH₃
(d) (CH₃)₂C = CHC₂H₅ (1)
Answer:
(d) (CH₃)₂C = CHC₂H₅

(ii) Draw the Newman projections of eclipsed and staggered conformations of ethane.
Answer:

Question 23.
(i) Excess concentration of which of the following in water causes the disease called ‘Blue baby syn-drome’?
(A) Fluoride
(B) Chloride
(C) Nitrate
(D) Sulphate (1)
Answer:
(C) Nitrate

(ii) What is smog? How is classical smog different from photochemical smog? (2)
Answer:
Smog is a mixture of smoke + fog

Photochemical smog	Classical smog
Occurs in the midday	Occurs in early morning
Due to the presence of oxides of nitrogen, formaldehyde	Due to the presence of oxides of sulphur
They are oxidising in nature	They are reducing in nature.

Answer any 5 questions from 24 to 31. Each carries 4 scores. (5 × 4 = 20)

Question 24.
Write the postulates of Bohr’s model for Hydrogen atom. Mention any two demerits of the model.
Answer:

• Electrons are revolving in circular path called orbit
• There are no energy change for an electron while revolving in an orbit.
• Energy is absorbed when an electron moves from lower energy level to higher energy level.
• Energy is released when an electron moves from higher energy level to lower energy level.
  ∆E = hυ
• Angular momentum of an electron revolving in the nh orbital are the integral multiples of \(\frac{nh}{2π}\).

Demerit

• 1. It couldn’t explain Heisenberg’s uncertainty principle and de Broglie wavelength
• It could not explain the fine spectrum of hydrogen atom.

Question 25.
Write the molecular orbital configuration of N₂. Calculate its bond order and predict its magnetic behaviour.
Answer:
M.O configuration of N₂

Bond order (B.O) = 1/2 [Nb – Na]
= 1/2 [10 – 4] = 1/2 × 6 = 3
N₂ is diamagnetic, due to the presence of paired electron in the highest occupied orbital.

Question 26.
(i) Define entropy. (1)
Answer:
Entropy is the degree of disorderness or randomness of a system

(ii) Explain by giving reason whether entropy in-creases or decreases in the following processes:
(a) A liquid crystallieses into a solid. (1)
(b) Temperature of a crystalline solid is raised from OK to 115 K. (1)
Answer:
(a) Entropy decreases. Because in liquid state disorder is more than crystalline solid state hence entropy decreases.
(b) Entropy increases. This is because when temperature increases, disorderness increases and hence the entropy increases.

(iii) Write the equation showing the relationship between entropy and Gibb’s energy. (1)
Answer:
Relationship between Entropy and Gibb’s energy is: G = H – TS

Question 27.
(i) Which of the following is a Lewis acid?
(A) HO^–
(B) F^–
(C) NH₃
(D) BCl₃ (1)
Answer:
(D) BCl₃

(ii) What are buffer solutions? Give example. (2)
Answer:
Solutions which resist the change in pH on dilution or with the addition of small amount of acid or alkali are called Buffer solutions. E.g. An equimolar mixture of acetic acid and sodium acetate

(iii) Which of the following is a salt of weak acid and strong base?
(A) CH₃COONa
(B) NH₄Cl
(C) CH₃COONH₄
(D) (NH₄)₂SO₄ (1)
Answer:
(A) CH₃COONa

Question 28.
(i) Write any two similarities between Lithium and Magnesium. (2)
Answer:
1. Li is Hard
2. Li forms monoxide

(ii) Describe the biological importance of sodium and calcium. (2)
Answer:
Sodium has an important role in nerve transmission of signals.
Ca is used for the strengthening of teeth and bone.

Question 29.
What happens when:
(i) Borax is heated. (2)
(ii) Boric acid is added to water. (1)
(iii) Diborane is treated with ammonia. (1)
Answer:

Question 30.
(i) Which of the following methods is used for the quantitative estimation of halogens in an organic compound?
(A) Dumas method
(B) Kjeldahl’s method
(C) Carius method
(D) Lassaigne’smethod (1)
Answer:
(C) Carius method

(ii) Briefly explain the principles of the following techniques used in the purification of organic compound:
(a) Sublimation (1)
(b) Crystallization (1)
(c) Distillation (1)
Answer:
(a) Sublimation: The compound in the solid form directly changes in to gaseous form, eg. Camphor can be purified by this method.
(b) Crystallisation: It is used for the solutions with difference in the solubilities of the compound and the impurities in a suitable solvent.
(c) Distillation: The liquids with different boiling point are boiled the vapours are collected and cooled to get pure solution.

Question 31.
(i) Propene reacts with HBr to form a mixture of two products. Identify and write the major and minor product in the mixture. (2)
Answer:

(ii) Complete the following equations:

Answer: