Kerala Plus Two Chemistry Board Model Paper 2022 with Answers

Reviewing Kerala Syllabus Plus Two Chemistry Previous Year Question Papers and Answers Pdf Board Model Paper 2022 helps in understanding answer patterns.

Kerala Plus Two Chemistry Board Model Paper 2022 with Answers

Time: 2 Hours
Maximum: 60 Scores

Part – I

A. Answer any five questions from 1 to 9. Each carries 1 score. (5 × 1 = 5)

Question 1.
Which of the following is a ferromagnetic substance?
(a) NaCl
(b) Co
(c) MnO
(d) H₂O
Answer:
(b) Co

Question 2.
The electrolyte used in Lead Storage battery is __________________
Answer:
H₂SO₄ = 38%

Question 3.
The concentration term that varies with temperature is
(a) Mass
(b) Mole fraction
(c) Molality
(d) Molarity
Answer:
(d) Molarity

Question 4.
The unit of rate constant of a first order reaction is __________________
Answer:
s^-1

Question 5.
Name the metal that can be purified by Mond’s process.
Answer:
Nickel (Ni)

Question 6.
Which of the following is a macromolecular colloid?
(a) Gold sol
(b) Sulphur sol
(c) Rubber latex
(d) As₂S₃ sol
Answer:
(c) Rubber Latex

Question 7.
Carbyl amine reaction is given by __________________
(a) CH₃ – NH₂
(b) CH₃ – CN
(c) CH₃ – NO
(d) CH₃ – NH – CH₃
Answer:
(a) CH₃ – NH₂

Question 8.
Find the product formed when formaldehyde reacts with CH₃ – Mg – Cl.
Answer:
CH₃ – CH₂ – OH

Question 9.
The chemical formula of phosgene is
(a) CaCl₂
(b) CHCl₃
(c) COCl₂
(d) PH₃
Answer:
(c) COCl₂

B. Answer all questions from 10 to 13. each carries 1 score. (4 × 1 = 4)

Question 10.
Which of the following bases is not present in RNA?
(a) Adenine
(b) Thymine
(c) Guanine
(d) Uracil
Answer:
(b) Thymine

Question 11.
The compounds required for the preparation of Bakelite are
(a) Urea, formaldehyde
(b) Phenol, formaldehyde
(c) Melamine, formaldehyde
(d) Phenol, Urea
Answer:
(b) Phenol, formaldehyde

Question 12.
Saccharin is used as
(a) Tranquilizer
(b) Food preservative
(c) Artificial sweetener
(d) Anti-oxidant
Answer:
(c) Artificial sweetener

Question 13.
During galvanisation the iron surface is coated with
(a) Mercury
(b) Zinc
(c) Tin
(d) Aluminium
Answer:
(b) Zinc

Part – II

A. Answer any two questions from 14 to 17. Each carries 2 scores. (2 × 2 = 4)

Question 14.
Distinguish between order and molecularity of chemical reaction.
Answer:

Order	Molecularity
1. It is the sum of the powers to which the concentration terms are raised in the rate equation.	1. No. of molecules taking part in the chemical reaction.
2. It can be in integral and zero.	2. It can be integral but not zero.
3. Experimental	3. Theoretical

Question 15.
What is Lanthanoid Contraction? Mention one consequence of it.
Answer:
The steady decrease in the atomic and ionic size of lanthanoids with increase in atomic number is known as lanthanoid contraction.
Consequences:

• Separation of Lanthanoid is difficult
• Zr and Hf are similar.

Question 16.
What is the chemical name of Hinsberg reagent? What is its use?
Answer:
Benzene sulphonyl chloride (C₆H₅SO₂Cl).
It is used to distinguish primary, secondary, and tertiary amines.

Question 17.
Calculate the osmotic pressure of 0.1 M glucose solution at 27°C (R = 0.082).
Answer:
π = CRT
= 0.1 × 0.082 × 300
= 2.46 atm

B. Answer any two questions from 18 to 20. Each carries 2 scores. (2 × 2 = 4)

Question 18.
Explain the behaviour of conductor and insulator using Band theory.
Answer:

Question 19.
How is Potassium Permanganate prepared?
Answer:
The preparation of Potassium permanganate from Pyrolusite (MnO₂) involves two steps.

1. MnO₂ is fused with KOH to form potassium manganate.
   2MnO₂ + 4KOH + O₂ → 2K₂MnO₄ + 2H₂O
2. Manganate ion on electrolytic oxidation in alkaline medium gives permanganate ion.
   \(\mathrm{MnO}_4^{2-} \longrightarrow \mathrm{MnO}_4^{-}\)

Question 20.
Write the two stages involved in the conversion of Aniline to Phenol.
Answer:

Part – III

A. Answer any three questions from 21 to 24. Each carries 3 scores. (3 × 3 = 9)

Question 21.
Distinguish between Schottky and Frenkel defect.
Answer:

Schottky Defect	Fenkel Defect
1. Equal number of cations and anions are missed from the lattice.	1. Cations are missing from the lattice and are seen in the interstitial space.
2. Density decreases.	2. No change in density.
3. Cations and anions are similar in size.	3. Cations and anions are large with a difference.

Question 22.
A first order reaction is 90% completed in 20 seconds. Find the rate constant and half-life period.
Answer:

Question 23.
What is Williamson’s synthesis? How is it used to prepare methoxy benzene?
Answer:
Alkyl halide reacts with sodium alkoxide to form ether. This reaction is called Williamson’s ether synthesis.
Or
R-X + R’-ONa’ → R-O-R’ + NaX
By Williamson synthesis, we can prepare methoxybenzene (Anisole) by treating sodium phenoxide (C₆H₅-ONa) with methyl bromide (CH₃-Br).
C₆H₅ – ONa + CH₃ – Br → C₆H₅ – O – CH₃ + NaBr

Question 24.
(i) What is Reimer-Tiemann reaction? (2)
(ii) Identify the products formed when phenol is treated with Bromine water. (1)
Answer:
(i)

Phenol reacts with chloroform in the presence of NaOH to form salicylaldehyde.
(ii)

B. Answer any two questions from 25 to 27. Each carries 3 scores. (2 × 3 = 6)

Question 25.
(i) What is Vant Hoff factor? (1)
(ii) The molar mass of benzoic acid measured from colligative property shows an abnormal value. Explain. (2)
Answer:
(i) Van’t Hoff factor (i) is defined as:

(ii) In benzoic acid, due to association of molecules, the total no. of molecules decreases. Hence colligative property decreases and molecular mass increases.

Question 26.
(i) Halo arenes are less reactive in nucleophilic substitution. Why? (2)
(ii) What is Wurtz-Fittig reaction? (1)
Answer:
(i) Due to the delocalisation of π electrons in the benzene ring halo arenes are less reactive in nucleophilic substitution reactions or resonance effect, sp² hybrid C atom is attached to halogen atom.
(ii) When a mixture of alkyl halide and aryl halide is treated with sodium in dry ether, an alkyl arene is formed. This reaction is called Wurtz-Fittig reaction.

Question 27.
(i) Explain the hydroboration-oxidation of propene. (2)
(ii) What is Wood Spirit? (1)
Answer:
(i) Hydroboration-Oxidation is according to Markovnikov’s addition due to the presence of H₂-O₂.

(ii) Wood spirit – methanol CH₃OH

Part – IV

A. Answer any three questions from 28 to 31. Each carries 4 scores. (3 × 4 = 12)

Question 28.
(i) What are Fuel Cells? Explain the working of H₂-O₂ fuel cell. (3)
(ii) Give any two advantages of fuel cells. (1)
Answer:
(i) Fuel cells are galvanic cells which convert the energy of combustion of fuels directly into electrical energy.
Working of H₂ – O₂ fuel cell:
Anode reaction: 2H₂ + 4OH^– → 4H₂O + 4e^–
Cathode reaction: O₂ + 2H₂O + 4e^– → 4OH^–
Overall reaction: 2H₂ (g) + O₂ (g) → 2H₂O (l)
(ii) The advantages of fuel cell are:

• Eco friendly
• By-product is pure water
• Continuously working

Question 29.
(i) Match the following:

Polymer	Monomer
HDP	Amino acid
Teflon	Ethylene
Protein	D-Glucose
Starch	Tetra fluoro ethene

(ii) What is Vulcanisation? How does it enhance the properties of rubber? (2)
Answer:
(i)

Polymer	Monomer
HDP	Ethylene
Teflon	Tetrafluoroethene
Protein	Amino acid
Starch	D-glucose

(ii) Heating rubber with sulphur to make natural rubber harder is known as vulcanisation. Sulphur cross links are formed between the monomer units.

Question 30.
(i) Hydrolysis of sucrose is called inversion of sugar. Why? (2)
(ii) Why is sucrose called a Non-reducing sugar? (2)
Answer:
(i) Dextro rotatory sucrose on hydrolysis gives a mixture of laevo rotatory. Thus hydrolysis of sucrose brings about a change in sign of rotation from dextro to laevo and the product is called invert sugar. This process is called inversion of sugar.
(ii) Those carbohydrates which do not contain free aldehyde or ketone group are called non-reducing sugars.
Eg. sucrose

Question 31.
(i) Explain the steps involved in the leaching of Bauxite. (3)
(ii) What is the role of Cryolite in the metallurgy of Aluminium? (1)
Answer:
(i) Bauxite is treated with NaOH. Then sodium aluminate is formed. To this solution CO₂ gas is passed. Sodium aluminate is precipitated as hydrated alumina. It is filtered and heated to get pure alumina.

(ii) Cryolite lowers the melting point of the mixture and brings conductivity.

B. Answer any one question from 32 to 33. Each carries 4 scores. (1 × 4 = 4)

Question 32.
(i) What is the Brownian movement? What is the reason for this movement? (2)
(ii) What are Zeolites? Write its use. (2)
Answer:
(i) Brownian movement: It is the zig-zag movement of colloidal particles.
(ii) Zeolite: Sodium Aluminum silicate.
They are used as a water softener, shape-selective catalyst.

Question 33.
(i) Distinguish between Anionic and Cationic detergents with example. (2)
(ii) What are broad spectrum antibiotics? Give an example. (2)
Answer:
(i)

Anionic Detergents	Cationic Detergents
1. They contain Na salts of sulpho-nated long chain alcohols or hydrocarbons.	1. They are quaternary ammonium salts of amines with acetates, chlorides or bromides.
2. The anionic part is used in the cleaning action.	2. Cationic part is the cause for cleaning action.
3. Used in toothpaste.	3. Used in Hair conditioner.
4. Sodium Lauryl sulphate or Sod. Dodecyl benzene sulphonate.	4. Cetyl trimethyl ammonium bromide or quarternary ammonium compounds.

(ii) Broad Spectrum Antibiotics: They are effective for a wide range of diseases.
(Antibiotics which kill or inhibit a wide range of Gram-positive and Gram-negative bacteria are called broad spectrum antibiotics).
eg. Chloramphenicol, Ampicillin

Part – V

Answer any two questions from 34 to 36. Each carries 6 scores. (2 × 6 = 12)

Question 34.
(i) What are the major steps involved in the contact process for the manufacture of sulphuric acid? (3)
(ii) What are interhalogen compounds? Give two examples. (2)
(iii) PCl₃ fumes in moist air. Why? (1)
Answer:
(i) Contact process involves the following steps:
S + O₂ → SO₂
SO₂ + O₂ → SO₃
SO₃ + H₂SO₄ → H₂S₂O₇ Oleum
(ii) Inter halogen compounds are formed by combining different halogen atoms, eg, BrF₅, CIF₃.
(iii) PCl₃ + H₂O → H₃PO₃ + HCl
PCl₃ reacts with H₂O to form fuming HCl

Question 35.
(i) What is Rosenmund’s reduction? (2)
(ii) Give the aldol condensation product of CH₃ – CHO. (1)
(iii) Which is the strongest acid – acetic acid, chloro acetic acid or fluoro acetic acid? Justify. (2)
Answer:
(i) Rosenmund reduction: Acid chlorides react with hydrogen in the presence of Pd supported on BaSO₄, we get aldehydes. This reaction is called Rosenmund’s reduction.
The equation:

(ii) Crotanaldehyde or, But-2-enal

(iii) Fluoroacetic acid: Due to the presence of -I effect (electron withdrawing) group.

Question 36.
(i) Give the IUPAC name of [Co(NH₃)₅Br]SO₄ and [Ni(CO)₄]. (2)
(ii) Explain Linkage isomerism with an example. (2)
(iii) Represent the geometrical isomers of [Co(NH₃)₄Cl₂]. (2)
Answer:
(i) [Co(NH₃)₅Br]SO₄ – Penta ammine bromido cobalt (III) sulphate
[Ni(CO)₄] – Tetracarbonylnickel(O)
(ii) Linkage isomerism is due to the difference in the linking atom.
eg: [Co(NH₃)₅ (NO₂)]Cl₂ – Linking the nitro group with Cobalt through Nitrogen atom
[Co(NH₃)₅(ONO)]Cl₂ – Linking the nitro group with Cobalt through oxygen atom
(iii) Geometrical isomers of [Co(NH₃)₄Cl₂]⁺