HSC Science (Computer Science) 12th Board ExamMaharashtra State Board
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Question Paper Solutions - Chemistry 2014 - 2015 HSC Science (Computer Science) 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

The hybridisation of phosphorus in phosphorus pentachloride is _______.

(A) dsp3

(B) sp3 d

(C) d2 sp3

(D) sp3 d2

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Compounds of Phosphorus
[1]1.2

The rate constant for a first order reaction is 100 s–1. The time required for completion of 50% of reaction is _______.

(A) 0.0693 milliseconds

(B) 0.693 milliseconds

(C) 6.93 milliseconds

(D) 69.3 milliseconds

Chapter: [5] Chemical Kinetics
Concept: Integrated Rate Equations - Half-life of a Reaction
[1]1.3

Silica is added to roasted copper ore during smelting process to remove _______.

(A) ferrous sulphide

(B) ferrous oxide

(C) cuprous sulphide

(D) cuprous oxide

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Occurrence of Metals
[1]1.4

96500 coulombs correspond to the charge on how many electrons?

(A) 1.6 X 1019

(B) 6.022 X 1020

(C) 6.022 X 1023

(D) 6.022 X 1024

Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction
[1]1.5

For the reaction: Cl2(g) → 2Cl(g), _______.

(A) ΔH is positive, ΔS is positive

(B) ΔH is positive, ΔS is negative

(C) ΔH is negative, ΔS is negative

(D) ΔH is negative, ΔS is positive

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Enthalpy of Bond Dissociation
[1]1.6

The substance ‘X’, when dissolved in solvent water gave molar mass corresponding to the molecular formula ‘X3’. The van’t Hoff factor (i) is _______.

(A) 3

(B) 0.33

(C) 1.3

(D) 1

Chapter: [2] Solutions and Colligative Properties
Concept: Abnormal Molar Masses
[1]1.7

The relation a ≠ b ≠ c and α ≠  β ≠  γ represents which crystal system?

(A) Orthorhombic

(B) Tetragonal

(C) Triclinic

(D) Monoclinic

Chapter: [1] Solid State
Concept: Amorphous and Crystalline Solids
[12]2 | Answer any SIX of the following:
[2]2.1

Define ebullioscopic constant. Write its unit.

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Elevation of Boiling Point
[2]2.2

State  Second law of thermodynamics in terms of entropy.

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Second and Third Law of Thermodynamics

State Third law of thermodynamics

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Second and Third Law of Thermodynamics
[2]2.3

What is the hybridisation of carbon atom in diamond and graphite?

Chapter: [1] Solid State
Concept: Amorphous and Crystalline Solids

0.1 mole of Buckminster fullerene contains how many kg of carbon? [Atomic mass of carbon = 12]

Chapter: [15] Polymers
Concept: Polymers - Classification of Polymers Based on Source
[2]2.4
[1]2.4.1

Draw structure of Chlorine trifluoride

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Interhalogen Compounds
[1]2.4.2

Draw structure of Chlorine pentafluoride

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Concept of Group 17 Elements
[2]2.5

Derive an expression for maximum work in isothermal reversible expansion of two moles of an ideal gas.

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - First Law of Thermodynamics
[2]2.6

Can copper sulphate solution be stored in an iron vessel? Explain.

Chapter: [4] Electrochemistry
Concept: Galvanic Cells - Introduction
[2]2.7

Define Average rate of reaction.

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

Define  Instantaneous rate of reaction.

Chapter: [5] Chemical Kinetics
Concept: Rate of a Chemical Reaction
[2]2.8

Define Hydrometallurgy?

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Oxidation Reduction

Define Electrometallurgy?

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Oxidation Reduction
[9]3 | Answer any THREE of the following:
[3]3.1

What is the action of dioxygen on Calcium

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Dioxygen

What is the action of dioxygen on Iron

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Dioxygen

What is the action of dioxygen on Carbon disulfide

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Dioxygen
[3]3.2

A solution of glucose in water is labelled as 10% (W/W).

Calculate:

a. Molality

b. Molarity of the solution.

[Given: Density of solution is 1.20 g mL-1 and molar mass of glucose is 180 g mol-1 ]

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Introduction
[3]3.3

Resistance of conductivity cell filled with 0.1 M KCl solution is 100 ohms. If the resistance of the same cell when filled with 0.02 M KCl solution is 520 ohms, calculate the conductivity and molar conductivity of 0.02 M KCl solution. [Given: Conductivity of 0.1 M KCl solution is 1.29 S m-1 .]

Chapter: [4] Electrochemistry
Concept: Conductance of Electrolytic Solutions - Variation of Conductivity and Molar Conductivity with Concentration
[3]3.4

Ammonia and oxygen react at high temperature as:

4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g) In an experiment, rate of formation of NO(g) is 3.6 x 10-3 mol L-1 s -1.

Calculate:

a. Rate of disappearance of ammonia.

b. Rate of formation of water.

Chapter: [5] Chemical Kinetics
Concept: Rate of a Chemical Reaction
[7]4 | Answer any ONE of the following:
[7]4.1

What is the effect of temperature on solubility of a gas in a liquid?

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

Explain refining of nickel by Mond process.

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Electrochemical Principles of Metallurgy

State Kohlrausch’s law of independent migration of ions.

Chapter: [4] Electrochemistry
Concept: Conductance of Electrolytic Solutions - Variation of Conductivity and Molar Conductivity with Concentration

Silver crystallises in F.C.C. (face-centred cubic crystal) structure. The edge length of the unit cell is found to be 408.7 pm. Calculate density of the unit cell.

[Given: Molar mass of silver is 108 g mol-1 ]

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Introduction
[7]4.2

Write ‘four’ uses of hydrochloric acid.

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

Write chemical formula of the following oxoacids of chlorine:

a. Hypochlorous acid

b. Chlorous acid

c. Chloric acid

d. Perchloric acid

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Oxoacids of Halogens

The equilibrium constant Kp for the reaction,

H2(g) + I2(g) → 2HI(g) is 130 at 510 K. Calculate ΔGo for the following reaction at the same temperature: 2HI(g) → H2(g) + I2(g) [Given: R = 8.314 J K-1 mol-1 ]

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Equilibrium Constant
[7]5 | Select and write the most appropriate answer from the given alternatives for each sub-question:
[1]5.1

Which among the following reducing agents is NOT used to reduce acetaldehyde to ethyl alcohol?

(A) Na-Hg and water

(B) Zn-Hg and conc. HCl

(C) H2-Raney Ni

(D) LiAlH4/H+

Chapter: [11.01] Alcohols
Concept: Alcohols - Methods of Preparation
[1]5.2

Acetaldehyde, when treated with which among the following reagents does NOT undergo addition reaction?

(A) Ammonia

(B) Hydroxylamine

(C) Ammoniacal silver nitrate

(D) Semicarbazide

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Nucleophilic Addition Reactions
[1]5.3

What is natural rubber?

(A) Cis-1,4-polyisoprene

(B) Neoprene

(C) Trans-1,4-polyisoprene

(D) Butyl rubber

Chapter: [15] Polymers
Concept: Types of Polymerisation Reactions - Rubber
[1]5.4

What is salvarsan?

(A) An antiseptic

(B) An antibiotic

(C) An antifertility drug

(D) An analgesic

Chapter: [16.01] Chemicals in Medicines
Concept: Drugs and Their Classification
[1]5.5

Which among the following vitamins is also known as riboflavin?

(A) B1

(B) B2

(C) B6

(D) B12

Chapter: [14.03] Vitamins
Concept: Vitamins - Important Vitamins, Their Sources and Their Deficiency Diseases
[1]5.6

The amine which reacts with nitrous acid to give yellow oily compound is _______.

(A) ethylamine

(B) isopropylamine

(C) secondary butylamine

(D) dimethylamine

Chapter: [13.01] Amines
Concept: Amines - Chemical Reactions of Amines - Reaction with Nitrous Acid
[1]5.7

What is the molecular formula of chromyl chloride?

(A) CrO2Cl2

(B) CrOCl2

(C) CrCl3

(D) Cr2OCl2

Chapter: [8.01] D-block Elements
Concept: D-block Elements - Some Important Compounds of Transition Elements
[12]6 | Answer any SIX of the following :
[2]6.1

Identify ‘A’ and ‘B’ in the following reaction :

CH3 - CH = CH`(HBr)/()` ‘A’ `(alc. KOH)/()` ‘B’

Chapter: [10.01] Haloalkanes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloalkanes - Elimination Reactions
[2]6.2

Distinguish between lanthanoid and actinoids.

Chapter: [8.02] F-block Elements
Concept: F-block Elements - The Actinoids
[2]6.3

How are the following compounds prepared?

Benzyl alcohol from benzyl chloride.

Chapter: [11.01] Alcohols
Concept: Alcohols - Methods of Preparation

How are the following compounds prepared?

Propan-1-ol from propanal

Chapter: [11.01] Alcohols
Concept: Alcohols - Methods of Preparation
[2]6.4

What is the action of acetic anhydride on ethylamine?

Chapter: [13.01] Amines
Concept: Amines - Chemical Reactions of Amines - Electrophilic Substitution

What is the action of acetic anhydride on diethylamine?

Chapter: [13.01] Amines
Concept: Amines - Chemical Reactions of Amines - Electrophilic Substitution
[2]6.5

What are monosaccharides?

Chapter: [14.01] Carbohydrates
Concept: Carbohydrates - Monosaccahrides

Draw ring structure of α - D - (+) - glucopyranose.

Chapter: [14.01] Carbohydrates
Concept: Carbohydrates - Monosaccahrides
[2]6.6

Explain Tranquilizers

Chapter: [16.01] Chemicals in Medicines
Concept: Drugs and Their Classification

Explain cationic detergents.

Chapter: [16.03] Cleansing Agents
Concept: Cleansing Agents - Soaps
[2]6.7

What is Stephen reaction?

Chapter: [13.02] Cyanides and Isocyanides
Concept: Cyanides and Isocyanides
[2]6.8

Explain Sidgwick’s electronic theory with suitable example

Chapter: [9] Coordination Compounds
Concept: Coordination Compounds - Introduction
[9]7 | Answer any THREE of the following :
[3]7.1

What is the action of nitrous acid on primary nitroalkane?

 

Chapter: [13.01] Amines
Concept: Amines - Identification of Primary, Secondary and Tertiary Amines

What is the action of nitrous acid on secondary nitroalkane?

Chapter: [13.01] Amines
Concept: Amines - Identification of Primary, Secondary and Tertiary Amines

What is the action of nitrous acid on tertiary nitroalkane

Chapter: [13.01] Amines
Concept: Amines - Identification of Primary, Secondary and Tertiary Amines
[3]7.2

What is peptide linkage?

Chapter: [14.02] Proteins
Concept: Proteins - Structure of Proteins

How is tripeptide formed?

Chapter: [14.02] Proteins
Concept: Proteins - Structure of Proteins
[3]7.3

Write the reactions involved in the preparation of Teflon

 

Chapter: [15] Polymers
Concept: Polymers - Preparation of Polytetrafluoroethene (Teflon)

Write the reactions involved in the preparation of Orlon

Chapter: [15] Polymers
Concept: Polymers - Preparation of Polyacrylonitrile

Write the reactions involved in the preparation of  PVC

Chapter: [15] Polymers
Concept: Polymers - Some Important Polymers
[3]7.4

What is the position of iron (Z = 26) in periodic table?

Chapter: [8.01] D-block Elements
Concept: Position in the Periodic Table

Explain why is Fe3+ more stable than Fe2+?

Chapter: [8.01] D-block Elements
Concept: General Properties of the Transition Elements (D-block)
[7]8 | Answer any ONE of the following:
[7]8.1

Discuss the mechanism of alkaline hydrolysis of bromomethane.

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

How is carbolic acid prepared from chlorobenzene?

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

What is the action of bromine water on carbolic acid?

Chapter: [11.02] Phenols
Concept: Phenols - Electrophillic Substitution Reactions

Write chemical test to distinguish between carbolic acid and alcohol.

Chapter: [11.02] Phenols
Concept: Phenols - Physical and Chemical Properties
[7]8.2

Explain cationic complexes and anionic complexes of co-ordination compounds.

Chapter: [9] Coordination Compounds
Concept: Isomerism in Coordination Compounds - Stereoisomerism

Write the structure and IUPAC names of isomeric aldehydes having molecular formula C5H10O.

Chapter: [9] Coordination Compounds
Concept: Nomenclature of Coordination Compounds - Naming of Mononuclear Coordination Compounds

Draw the structure of aspirin.

Chapter: [11.02] Phenols
Concept: Phenols - Physical and Chemical Properties
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