HSC Science (Computer Science) 12th Board ExamMaharashtra State Board
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# Question Paper Solutions for Chemistry 2013-2014 HSC Science (Computer Science) 12th Board Exam

Marks: 70
[7]1 | Answer any ONE of the following
[7]1.1

Define boiling point

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

Define cell constant.

Chapter: [4] Electrochemistry
Concept: Conductance of Electrolytic Solutions - Introduction

Derive a relation between ΔH and ΔU for a chemical reaction. Draw neat labelled diagram of calomel electrode. Resistance and conductivity of a cell containing 0.001 M KCI solution at 298K are 1500Ω and 1.46x10-4 S.cm-1 respectively.

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - First Law of Thermodynamics
[7]1.2

Write molecularity of the following reaction:

2NO(g)+O2(g)→2NO2(g)

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

What is calcination?

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

How does it differ from 'roasting"?

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

Write resonating structures of ozone.

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

The decomposition of N2O5(g) at 320K according to the following equation follows first order reaction:

N_2O_(5(g))->2NO_(2(g))+1/2O_(2(g))

The initial concentration of N2O5(g) is 1.24 x 10-2 mol. L-1 and after 60 minutes 0.20x10-2 molL-1. Calculate the rate constant of the reaction at 320K.

Chapter: [5] Chemical Kinetics
Concept: Factors Influencing Rate of a Reaction
[9]2 | Answer any THREE of the following:
[3]2.1

One mole of a gas expands by 3L against a constant pressure of 3 atmosphere. Calculate the work done in -

(a) L.atmosphere

(b) Joules

(c) Calories

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Work, Heat, Energy, Extensive and Intensive Properties
[3]2.2

Calculate the amount of CaCl2 (van't Hoff factor i = 2·47) dissolved in 2·5 L solution so that its osmotic pressure at 300K is 0·75 atmosphere.

Given : Molar mass of CaCl2 is 111g mol-1

R=0.082 L.atm K-1mol-1

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Introduction
[3]2.3

Describe anomalous behaviour of fluorine with the other elements of group 17 wilh reference to :

(a) Hydrogen bonding

(b) Oxidation state

(c) Polyhalide ions

Chapter: [7.03] Group 17 Elements
Concept: P - Block Group 17 Elements - Anomalous Behaviour of Fluorine
[3]2.4

Face centred cubic crystal lattice of copper has density of 8.966 g.cm-3. Calculate the volume of the unit cell. Given molar mass of copper is 63.5 g mol-1 and Avogadro number Nis 6.022 x 1023 mol-1

Chapter: [1] Solid State
Concept: Number of Atoms in a Unit Cell
[12]3 | Answer any SIX of the following
[2]3.1

What is the action of the following reagents on ammonia: Nessler's reagentl

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Ammonia

What is the action of the following reagents on ammonia: Sodium metal

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Ammonia
[2]3.2

State the first law of electrolysis

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

State second law of electrolysis

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

Draw neat and labelled diagram of Bessermer converter used in the extraction of copper.

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

Derive the relation between half life and rate constant for a first order reaction

Chapter: [5] Chemical Kinetics
Concept: Integrated Rate Equations - Half-life of a Reaction
[2]3.5

Derive the relation between DeltaG^@and equilibrium constant (K) for the reaction -

aA_bB ⇌ cC+dD.

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Equilibrium Constant
[2]3.6

Explain brown ring test with the help of chemical equation

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Nitric Acid
[2]3.7

Explain, why do aquatic animals prefer to stay at lower level of water during summer?

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

Distinguish between crystalline solid and amorphous solid

Chapter: [1] Solid State
Concept: Amorphous and Crystalline Solids
[7]4 | Select and write the most appropriate answer from the alternative given below each sub-quest.ion :
[1]4.1

To prepare n-type semiconductor the impurity to be added to silicon should have the following number of valence electrons:

(a) 2

(b) 3

(c) 4

(d) 5

Chapter: [1] Solid State
Concept: Electrical Properties - Applications of N-type and P-type Semiconductors
[1]4.2

Number of faradays of electricity required to liberate 12 g of hydrogen is:

(a) 1

(b) 8

(c) 12

(d) 16

Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction
[1]4.3

What is molecular formula of oleum?

(a) H2SO3

(b) H2SO4

(c) H2S2O7

(d) H2S2O8

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Sulphuric Acid
[1]4.4

Purification of aluminium by electrolytic refining is carried out by

(a)Hoope process

(b)Hall process

(c)Baeyer process

(d)Serperck process

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Occurrence of Metals
[1]4.5

The rate of reaction for certain reaction is expressed as :

1/3(d[A])/dt=-1/2(d[B])/dt=-(d[C])/dt

The reaction is

(a) 3A→2B+C

(b) 2B→3A+C

(c) 2B+C→3A

(d) 3A+2B→C

Chapter: [5] Chemical Kinetics
Concept: Rate of a Chemical Reaction
[1]4.6

A system absorbs 640 J heat and does work of 260 J, the change in internal energy of the system will be

(a) +380J

(b) -380J

(c) +900J

(d) -900J

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Internal Energy and Enthalpy
[1]4.7

Which of the following is not a colligative property?

(a) Vapour pressure

(b) Depression in freezing point

(c) Elevation in boiling point

(d) Osmotic pressure

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Osmosis and Osmotic Pressure
[7]5.1

Write the structural formula and IUPAC names of all possible isomers of the compound with molecular formula C3H8O.

Chapter: [11.02] Phenols
Concept: Phenols - Uses of Phenols

Write 'two' uses of phenol.

Chapter: [11.02] Phenols
Concept: Phenols - Uses of Phenols

What happens when glucose is treated with Bromine water

Chapter: [11.02] Phenols
Concept: Phenols - Uses of Phenols

What happens when glucose is treated with - Dilute nitric acid

Chapter: [11.02] Phenols
Concept: Phenols - Uses of Phenols

What happens when glucose is treated with Hydrogen cyanite (HCN)

Chapter: [11.02] Phenols
Concept: Phenols - Uses of Phenols
[7]5.2

Write the molecular formula and structural formula of BHA and BHT.

Chapter: [15] Polymers
Concept: Types of Polymerisation Reactions - Addition Polymerisation Or Chain Growth Polymerisation

Write a note on aldol condensation.

Chapter: [15] Polymers
Concept: Types of Polymerisation Reactions - Condensation Polymerisation Or Step Growth Polymerisation

What are thermoplastic polymers?

Chapter: [15] Polymers
Concept: Types of Polymerisation Reactions - Condensation Polymerisation Or Step Growth Polymerisation
[3]6.1

What is the action of the following reagents on aniline?

Bromine water

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

What is the action of the following reagents on aniline?

Acetic anhydride

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

What is the action of the following reagents on aniline?

Hot and cone. sulphuric acid

Chapter: [13.01] Amines
Concept: Amines - Chemical Reactions of Amines - Electrophilic Substitution
[3]6.2

Discuss the optical activity of lactic acid.

Chapter: [14.02] Proteins
Concept: Proteins - Structure of Proteins
[3]6.3

Write balanced chemical equations for action of potassium permanganate on: Hydrogen

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Oxides of Nitrogen

Write balanced chemical equations for action of potassium permanganate on Warm conc. sulphuric acid

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Oxides of Nitrogen

Explain why Mn2+ ion is more stable than Mn3+? (Given : Mn→ Z=25)

Chapter: [7.01] Group 15 Elements
Concept: P - Block Group 15 Elements - Oxides of Nitrogen
[3]6.4

What is effective atomic number (EAN.)?

Chapter: [9] Coordination Compounds
Concept: Coordination Compounds - Importance of Coordination Compounds

What is effective atomic number (EAN.)?

Chapter: [9] Coordination Compounds
Concept: Coordination Compounds - Importance of Coordination Compounds

Calculate EAN of cobalt (Z=27) in [CO(NH3)6]+3 and of zinc (Z=30) in [Zn(NH3)4]SO4.

Chapter: [9] Coordination Compounds
Concept: Coordination Compounds - Importance of Coordination Compounds

Calculate EAN of cobalt (Z=27) in [CO(NH3)6]+3 and of zinc (Z=30) in [Zn(NH3)4]SO4.

Chapter: [9] Coordination Compounds
Concept: Coordination Compounds - Importance of Coordination Compounds
[2]7.1

What is a soap ?

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

How soap is prepared?

Chapter: [16.03] Cleansing Agents
Concept: Cleansing Agents - Soaps
[2]7.2

Identify the compounds 'A' and 'B' in the following equation:

Chapter: [13.01] Amines
Concept: Amines - Preparation of Amines
[2]7.3

Write a note on self oxidation-reduction reaction of aldehyde with suitable example.

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Other Reactions
[2]7.4

Write names and chemical formulae of monomers used in preparing Buna-S.

Chapter: [15] Polymers
Concept: Types of Polymerisation Reactions - Rubber
[2]7.5

Define complex lipids

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

Mention 'two' functions of lipids

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

Distinguish between SN1 and SN2 mechanisms.

Chapter: [5] Chemical Kinetics
Concept: Factors Influencing Rate of a Reaction
[2]7.7

What are lanthanoids?

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

What is the position of actinoids in periodic table ?

Chapter: [8.02] F-block Elements
Concept: F-block Elements - The Actinoids
[2]7.8

How is Methoxyethane prepared from : Methyl iodide

Chapter: [11.03] Ethers
Concept: Ethers - Physical and Chemical Properties of ether

How is Methoxyethane prepared from : Diazomethane

Chapter: [11.03] Ethers
Concept: Ethers - Physical and Chemical Properties of ether
[7]8 | Select and write the most appropriate answer from the given alternatives for each sub-question
[1]8.1

IUPAC name of K4[Fe(CN)6] is

(a) tetrapotassium ferrocyanide

(b) potassium ferricyanide

(c) potassium ferrocyanide

(d) potassium hexacyanoferrate

Chapter: [9] Coordination Compounds
Concept: Nomenclature of Coordination Compounds - Naming of Mononuclear Coordination Compounds
[1]8.2

Carbon atom in methyl carbocation contains how many pairs of electrons?

(a) 8

(b) 4

(c) 3

(d) 5

Chapter: [11.03] Ethers
Concept: Ethers - Physical and Chemical Properties of ether
[1]8.3

How many moles of acetic anhydride will be required to form glucose pentaacetate from 2M of glucose?

(a) 2

(b) 5

(c) 10

(d) 2.5

Chapter: [14.01] Carbohydrates
Concept: Carbohydrates - Structures of Glucose
[1]8.4

Identify the weakest base amongst the following :

(a) p- methoxyaniline

(b) o-toluidine

(c) benzene - 1, 4 - diamine

(d) 4 - aminobenzoic acid

Chapter: [13.01] Amines
Concept: Physical Properties of Amines
[1]8.5

Bakelite is the polymer of:

(a) Benzaldchyde and phenol

(b) Acetaldehyde and phenol

(c) Formaldehyde and phenol

(d) Formaldehyde and benzyl alcohol

Chapter: [15] Polymers
Concept: Polymers - Some Important Polymers
[1]8.6

Formalin is 40% aqueous solution of:

(a) Methanal

(b) Methanoic acid

(c) Methanol

(d) Methanamine

Chapter: [12.01] Aldehydes and Ketones
Concept: Uses of Aldehydes and Ketones
[1]8.7

Which among the following pairs of elements is 'not' an example of chemical twins?

(a) Zr and Hf

(b) Nb and Ta

(c) Mo and W

(d) Ta and Re

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