HSC Science (Electronics) 12th Board ExamMaharashtra State Board
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Question Paper Solutions - Chemistry 2012 - 2013 HSC Science (Electronics) 12th Board Exam


Marks: 70
[7]1 | Select and write the most appropriate answer from the given alternatives for each sub-question:
[1]1.1

In Van Arkel method of refining metal, impure zirconium is converted to unstable volatile
compound by heating it with _______.

(A) oxygen

(B) chlorine

(C) bromine

(D) iodine

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: General Principles and Processes of Isolation of Elements - Principles and Methods of Extraction - Concentration
[1]1.2

The temperature at which vapour pressure of a liquid becomes equal to the atmospheric
pressure is _______.

(A) melting point

(B) boiling point

(C) 273 K

(D) 373 K

 

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Relative Lowering of Vapour Pressure
[1]1.3

Which of the following parameters are correct for triclinic lattice?

(A) α = β = γ = 90° and a = b = c

(B) α ≠ β ≠ γ = 90° and a ≠ b ≠ c

(C) α = γ = 90°, β ≠ 90° and a ≠ b ≠ c

(D) α ≠ β ≠ γ ≠ 90° and a ≠ b ≠ c

Chapter: [1] Solid State
Concept: Crystal Lattices and Unit Cells - Introduction
[1]1.4

Which mixture is used for respiration by deep sea divers?

(A) He + O2

(B) Ne + O2

(C) Ar + O2

(D) Kr + O2

Chapter: [2] Solutions and Colligative Properties
Concept: Solubility - Solubility of a Gas in a Liquid
[1]1.5

For the reaction, 2N2O5(g) → 4NO2(g) + O2(g) in liquid bromine, which of the following rate
equation is INCORRECT?

a) `-1/2 (d[N_2O_5])/dt`

b) `-1/4 (d[NO_2])/dt`

c) `(d[O_2])/dt`

d) `1/4 (d[NO_2])/dt`

Chapter: [5] Chemical Kinetics
Concept: Rate of a Chemical Reaction
[1]1.6

For a certain reaction, ∆H = − 50 kJ and ∆S = − 80 J K-1, at what temperature does the
reaction turn from spontaneous to non-spontaneous?

(A) 6.25 K

(B) 62.5 K

(C) 625 K

(D) 6250 K

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Work, Heat, Energy, Extensive and Intensive Properties
[1]1.7

What is the ratio of volumes of H2 and O2 liberated during electrolysis of acidified water?

(A) 1 : 2

(B) 2 : 1

(C) 1 : 8

(D) 8 : 1

Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction
[9]2 | Answer any THREE of the following:
[3]2.1

Calculate ∆H° for the following reaction:

2H3BO3(aq) → B2O3(s) + 3H2O(l)

a) H3BO3(aq) → HBO2(aq) + H2O(l) , ∆`H_1^@` = − 0.02 kJ

b) H2B4O7(s) → 2B2O3(s) + H2O(l) , ∆`H_2^@` = 17.3 kJ

c)H2B4O7(s) + H2O(l) → 4HBO2(aq), ∆`H_3^@` = − 11.58 kJ

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Enthalpy of Bond Dissociation
[3]2.2

Calculate molarity and molality of 6.3% solution of nitric acid having density 1.04 g cm−3
. (H = 1, N = 14, O = 16)

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Nitric Acid
[3]2.3

What is the action of chlorine (Cl) on the following:

Cold and dilute caustic soda

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Chlorine

What is the action of chlorine (Cl) on the following:

Hot and concentrated caustic soda

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Chlorine

What is the action of chlorine (Cl) on the following:

Potassium bromide solution

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Chlorine
[3]2.4

Calculate the number of atoms present in 2 gram of crystal which has face-centred cubic
(FCC) crystal lattice having edge length of 100 pm and density 10 gcm−3

Chapter: [1] Solid State
Concept: Crystal Lattices and Unit Cells - Introduction
[12]3 | Answer any SIX of the following:
[2]3.1

NF3 is possible, but NF5 is not. Why?

Chapter: [8.01] D-block Elements
Concept: General Properties of the Transition Elements (D-block)
[2]3.2

State second law of electrolysis

Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction

Explain Faraday’s second law of electrolysis

Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction
[2]3.3

Describe ‘froth floatation process’ for concentration of sulphide ore.

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Refining
[2]3.4

Distinguish between : Order and Molecularity of reaction

Chapter: [5] Chemical Kinetics
Concept: Factors Influencing Rate of a Reaction
[2]3.5

What are the conditions for spontaneous and non-spontaneous reactions in terms of free
energy change?

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Free Energy Change for Spontaneous and Non Spontaneous Processes

Define entropy.

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Free Energy Change for Spontaneous and Non Spontaneous Processes
[2]3.6

Draw the structure of H4P2O6 hypophosphoric acid

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Compounds of Phosphorus

What is the action of heat on potassium permanganate?

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Work, Heat, Energy, Extensive and Intensive Properties
[2]3.7

State Henry’s law.

Chapter: [2] Solutions and Colligative Properties
Concept: Solubility - Solubility of a Gas in a Liquid

How does solubility of a gas in water varies with the temperature?

Chapter: [2] Solutions and Colligative Properties
Concept: Solubility - Solubility of a Gas in a Liquid
[2]3.8

Define the following term

Schottky defect

Chapter: [1] Solid State
Concept: Imperfections in Solids - Introduction

What are Frenkel defect

Chapter: [1] Solid State
Concept: Imperfections in Solids - Introduction
[7]4 | Answer any ONE of the following:
[7]4.1

Write electrode reaction and net cell reaction for fuel cell. Calculate e.m.f. of the following cell at 25 °C.

Standard reduction potential (SRP) of Zn and Cu are − 0.76 V and 0.334 V respectively

Chapter: [4] Electrochemistry
Concept: Batteries - fuel cell

Define isotonic solutions

Chapter: [2] Solutions and Colligative Properties
Concept: Types of Solutions

Derive the relation ∆H − ∆U = ∆nRT.

Chapter: [2] Solutions and Colligative Properties
Concept: Solubility - Solubility of a Solid in a Liquid
[7]4.2

Define activation energy.

Chapter: [5] Chemical Kinetics
Concept: Temperature Dependence of the Rate of a Reaction

Calculate activation energy for a reaction of which rate constant becomes four times when temperature changes from 30 °C to 50 °C. (Given R = 8.314 JK−1 mol−1). 

Chapter: [5] Chemical Kinetics
Concept: Temperature Dependence of the Rate of a Reaction

Draw a neat, well labelled diagram of electrolytic cell for extraction of aluminium

Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction

Write electronic configuration and two uses of neon. (Z = 10)

Chapter: [7.04] Group 18 Elements
Concept: P - Block Group 18 Elements - Concept of Group 18 Elements
[7]5 | Select and write the most appropriate answer:
[1]5.1

When KOH solution is added to potassium dichromate solution the colour of solution
changes to yellow, because _______

(A) chromate ion changes to dichromate ion

(B) dichromate ion changes to chromate ion

(C) oxidation number of chromium changes from + 6 to + 4

(D) oxidation number of chromium changes from + 4 to +6

Chapter: [2] Solutions and Colligative Properties
Concept: Expressing Concentration of Solutions
[1]5.2

But-1-ene on reaction with HCl in the presence of sodium peroxide yields _______.

(A) n-butyl chloride

(B) isobutyl chloride

(C) secondary butyl chloride

(D) tertiary butyl chloride

Chapter: [10.01] Haloalkanes
Concept: Haloalkanes and Haloarenes - Nomenclature
[1]5.3

3-Methylbutane-2-ol on heating with HI gives ______

(A) 2-iodo-3-methylbutane

(B) 2-iodo-2-methylbutane

(C) 1-iodo-3-methylbutane

(D) 1-iodo-2-methylbutane

Chapter: [11.01] Alcohols
Concept: Alcohols, Phenols and Ethers - Nomenclature

3-Methylbutane-2-ol on heating with HI gives ______

(A) 2-iodo-3-methylbutane

(B) 2-iodo-2-methylbutane

(C) 1-iodo-3-methylbutane

(D) 1-iodo-2-methylbutane

Chapter: [11.02] Phenols
Concept: Alcohols, Phenols and Ethers - Nomenclature

3-Methylbutane-2-ol on heating with HI gives ______

(A) 2-iodo-3-methylbutane

(B) 2-iodo-2-methylbutane

(C) 1-iodo-3-methylbutane

(D) 1-iodo-2-methylbutane

Chapter: [11.03] Ethers
Concept: Alcohols, Phenols and Ethers - Nomenclature
[1]5.4

IUPAC name of is C6H5 − CH2 − C − CH2 − CH2 − CH2 − CH3 is _______

(A) 1-Phenylhexan-2-one

(B) 6-Phenylhexan-5-one

(C) 1-Benzylhexan-5-one

(D) Dodecan-5-one

Chapter: [10.01] Haloalkanes
Concept: Haloalkanes and Haloarenes - Nomenclature
[1]5.5

Iodoform is used as an _______.

(A) antiseptic

(B) antibiotic

(C) insecticide

(D) anaesthetic

Chapter: [11.01] Alcohols
Concept: Alcohols, Phenols and Ethers - Nomenclature

Iodoform is used as an _______.

(A) antiseptic

(B) antibiotic

(C) insecticide

(D) anaesthetic

Chapter: [11.02] Phenols
Concept: Alcohols, Phenols and Ethers - Nomenclature

Iodoform is used as an _______.

(A) antiseptic

(B) antibiotic

(C) insecticide

(D) anaesthetic

Chapter: [11.03] Ethers
Concept: Alcohols, Phenols and Ethers - Nomenclature
[1]5.6

Stachyose is an example of _______.

(A) monosaccharides

(B) disaccharides

(C) trisaccharides

(D) tetrasaccharides

Chapter: [14.01] Carbohydrates
Concept: Carbohydrates - Preparation of Glucose from Sucrose (Cane Sugar) and Starch
[1]5.7

The Zieglar-Natta catalyst is used in the preparation of _______.

(A) LDPE

(B) PHBV

(C) PAN

(D) HDPE

Chapter: [15] Polymers
Concept: Polymers - Some Important Polymers
[9]6 |  Answer any THREE of the following:
[3]6.1

How is phenol converted into the following?

benzene

Chapter: [11.01] Alcohols
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

benzene

Chapter: [11.02] Phenols
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

benzene

Chapter: [11.03] Ethers
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

benzoquinone

Chapter: [11.01] Alcohols
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

benzoquinone

Chapter: [11.02] Phenols
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

benzoquinone

Chapter: [11.03] Ethers
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

picric acid

Chapter: [11.01] Alcohols
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

picric acid

Chapter: [11.02] Phenols
Concept: Alcohols, Phenols and Ethers - Nomenclature

How is phenol converted into the following?

picric acid

Chapter: [11.03] Ethers
Concept: Alcohols, Phenols and Ethers - Nomenclature
[3]6.2

Write mechanism of Aldol addition reaction.

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Reactivity of Alpha Hydrogen in Aldehydes
[3]6.3

Enlist the properties of glucose that can not be explained on the basis of open chain structure of it

Chapter: [14.01] Carbohydrates
Concept: Carbohydrates - Structures of Glucose
[3]6.4

How is nitromethane prepared from the following?

alkyl halide

Chapter: [10.01] Haloalkanes
Concept: Haloalkanes and Haloarenes - Nomenclature

How is nitromethane prepared from the following?

α-halogen carboxylic acid

Chapter: [12.02] Carboxylic Acids
Concept: Chemical Properties and Reactions of Carboxylic Acid

How is nitromethane prepared from the following?

α-nitroalkene

Chapter: [10.01] Haloalkanes
Concept: Haloalkanes and Haloarenes - Nomenclature
[12]7
[2]7.1

How is methoxy benzene prepared from carbolic acid?

Chapter: [12.02] Carboxylic Acids
Concept: Carboxylic Acids - Methods of Preparation of Carboxylic Acids
[2]7.2

State the superiority of crystal field theory over valence bond theory.

Chapter: [9] Coordination Compounds
Concept: Bonding in Coordination Compounds - Crystal Field Theory (CFT)
[2]7.3

How is Benzonitrile converted to Benzophenone?

Chapter: [9] Coordination Compounds
Concept: Definitions of Some Important Terms Pertaining to Coordination Compounds
[2]7.4

Write a short note on Hoffmann bromamide degradation.

Chapter: [13.01] Amines
Concept: Amines - Preparation of Amines
[2]7.5

What are hormones?

Chapter: [14.02] Proteins
Concept: Proteins - Structure, Classification and Functions

State the function of insulin.

Chapter: [14.02] Proteins
Concept: Proteins - Structure, Classification and Functions
[2]7.6

How are polymers classified on the basis of polymerisation process?

Chapter: [15] Polymers
Concept: Polymers - Classification of Polymers Based on Source
[2]7.7

Explain any two chemical methods of food preservation.

Chapter: [16.02] Chemicals in Food
Concept: Chemicals in Food - Artificial Sweetening Agents and Food Preservatives
[2]7.8

Write observed electronic configuration of elements from first transition series having half
filled d-orbitals.

Chapter: [8.01] D-block Elements
Concept: D-block Elements - Some Important Compounds of Transition Elements
[7]8 | Answer any ONE of the following:
[7]8.1

What is lanthanoid contraction?

Chapter: [8.02] F-block Elements
Concept: F-block Elements - The Lanthanoids

Explain the cause of lanthanoid contraction?

Chapter: [8.02] F-block Elements
Concept: F-block Elements - The Lanthanoids

Explain effects of lanthanoid contraction

Chapter: [8.02] F-block Elements
Concept: F-block Elements - The Lanthanoids

Write the structure of melamine.

Chapter: [15] Polymers
Concept: Polymers - Some Important Polymers

Explain the cleansing action of soaps.

Chapter: [16.03] Cleansing Agents
Concept: Cleansing Agents - Soaps
[7]8.2

Explain optical activity of lactic acid

Chapter: [9] Coordination Compounds
Concept: Werner’S Theory of Coordination Compounds

Draw a neat, labelled energy profile diagram for SN1 reaction mechanism.

Chapter: [10.01] Haloalkanes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloalkanes - Elimination Reactions

Write applications of co-ordination compounds in medicine and electroplating.

Chapter: [9] Coordination Compounds
Concept: Definitions of Some Important Terms Pertaining to Coordination Compounds

Explain the structure of carbonyl functional group

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Nature of Carbonyl Group
S