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

p - type semi-conductors are made by mixing silicon with impurities of-

  1. germanium
  2. boron
  3. arsenic  
  4. antimony
Chapter: [1] Solid State
Concept: Electrical Properties - Applications of N-type and P-type Semiconductors
[1]1.2

Amongst the following identify the criterion for a process to be at equilibrium -

  1. ΔG < 0
  2. ΔG > 0
  3. ΔStotal=0
  4. ΔS < 0
Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Equilibrium Constant
[1]1.3

Colligative property depends only on ........................ in a solution.

  1. Number of solute particles.
  2. Number of solvent particles.
  3. Nature of solute particles.
  4. Nature of solvent particles.
Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Introduction
[1]1.4

The charge of how many coulomb is required to deposit 1.0 g of sodium metal (molar mass 23.0 g mol-1) from sodium ions is -

  1. 2098
  2. 96500
  3. 193000
  4. 4196
Chapter: [4] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction
[1]1.5

What is the chemical composition of malachite?

  1. CuO . CuC03
  2. Cu(OH)2 CuC03
  3. CuO.Cu(OH)2         
  4. Cu2O . Cu(OH)2
Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Occurrence of Metals
[1]1.6

The element that does NOT exhibit allotropy is

  1. As
  2. Sb
  3. Bi
  4. N
Chapter: [7.01] Group 15 Elements
Concept: Concept of Group 15 Elements
[1]1.7

The integrated rate equation for first order reaction is A → products

(a) `k=2.303t log_10([A]_@/[A]_t)`

(b) `k=-1/tl_n[A]_t/[A]_0`

(c) `k=2.303/t log_10 ([A]_t/[A]_0 )`

(d) `k=1/tl_n[A]_t/[A]_0`

Chapter: [5] Chemical Kinetics
Concept: Integrated Rate Equations - Half-life of a Reaction
[12]2 | Answer any SIX of the following
[2]2.1

Define the Enthalpy of fusion

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

Define the Enthalpy of atomization

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Internal Energy and Enthalpy
[2]2.2

Derive van’t Hoff general solution equation

Chapter: [2] Solutions and Colligative Properties
Concept: Abnormal Molar Masses
[2]2.3

Explain impurity defect in stainless steel with diagram

Chapter: [1] Solid State
Concept: Imperfections in Solids - Introduction
[2]2.4

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]2.5

Draw neat and labelled diagram of dry cell.

Chapter: [4] Electrochemistry
Concept: Batteries - Primary Batteries
[2]2.6

Explain the structure of sulphur dioxide.

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Sulphur Dioxide
[2]2.7

What is calcination?

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

Explain calcination with reactions.

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Oxidation Reduction
[2]2.8

Arrange the following reducing agents in the order of increasing strength under standard state conditions. Justify the answer 

Element

Al(s)

Cu(s)

Cl(aq)

Ni(s)

 

Eo

-1.66V

0.34V

1.36V

-0.26V

 

Chapter: [4] Electrochemistry
Concept: Galvanic Cells - Introduction
[9]3 |  Answer any THREE of the following
[3]3.1

Determine whether the reactions with the following ΔH and ΔS values are spontaneous or non-spontaneous. State whether the reactions are exothermic or endothermic.

(a) ΔH = -110kJ, ΔS = + 40JK-1 at 400 K

(b) ΔH = + 40kJ, ΔS = -120JK-1 at 250K

Chapter: [3] Chemical Thermodynamics and Energetic
Concept: Chemical Thermodynamics and Energetic - Work, Heat, Energy, Extensive and Intensive Properties
[3]3.2

1.0 x10-3Kg of urea when dissolved in 0.0985 Kg of a solvent, decreases freezing point of the solvent by 0.211 k. 1.6x10 Kg of another non-electrolyte solute when dissolved in 0.086 Kg of the same solvent depresses the freezing point by 0.34 K. Calculate the molar mass of the another solute. (Given molar mass of urea = 60)

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

Sucrose decomposes in acid solution into glucose and fructose according to the first order rate law with t1/2= 3 hours. What fraction of the sample of sucrose remains after 8 hours?

Chapter: [5] Chemical Kinetics
Concept: Integrated Rate Equations - Half-life of a Reaction
[3]3.4

Explain how does nitrogen exhibit anomalous behaviour amongst group 15 elements.

Chapter: [7.01] Group 15 Elements
Concept: Concept of Group 15 Elements
[7]4 | Answer any one of the following :
[7]4.1

Niobium crystallises as body centred cube (BCC) and has density of 8.55 Kg / dm-3 . Calculate the attomic radius of niobium.

(Given : Atomic mass of niobium = 93).

 

Chapter: [1] Solid State
Concept: Calculations Involving Unit Cell Dimensions

Write one statement of first law of thermodyamics and its mathematical expression.

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

Write the reactions involved in th'e zone of reduction in blast furnace during extraction of iron.

Chapter: [6] General Principles and Processes of Isolation of Elements
Concept: Occurrence of Metals
[7]4.2

Write molecular formulae and structures of Dithionic acid

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Oxoacids of Sulphur

Write molecular formulae and structures of the Peroxy monosulphuric acid

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Oxoacids of Sulphur

Write molecular formula and structure of Pyrosulphuric acid 

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Oxoacids of Sulphur

Write molecular formulae and structures of the Dithionous acid

Chapter: [7.02] Group 16 Elements
Concept: P - Block Group 16 Elements - Oxoacids of Sulphur

Calculate E and AG for the following at 28°C:

Mg(s) + Sn2+(0.04M) → Mg2+(0.06M) + Sn(s)

Ecell = 2.23V

Is the reaction spontaneous?

Chapter: [4] Electrochemistry
Concept: Galvanic Cells - Introduction
[7]5 | Select and write the most appropriate answers from the given alternatives for each sub-question
[1]5.1

Identify the product ‘D’ in the following sequence of reactions:

`H3C-CH2-CH2-Cl (Alc)/(KOH)'B'(HBr)/()'C'(Na)/(Ether)’D'`

  1. 2,2 - dimethyl butane  
  2. 2,3- dimethylbutane
  3. hexane                           
  4. 2,4 - dimethylpentane
Chapter: [10.01] Haloalkanes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloalkanes - Elimination Reactions
[1]5.2

Which of the following complexes will give a white precipitate on treatment with a solution of barium nitrate?

  1. [Cr(NH3)4SO4] Cl
  2. [Co(NH3)4Cl2] NO2
  3. [Cr(NH3)4Cl2]SO4
  4. [CrCl2(H2O)4]Cl
Chapter: [9] Coordination Compounds
Concept: Bonding in Coordination Compounds - Colour in Coordination Compounds
[1]5.3

What is the geometry of chromate ion?

  1. Tetrahedral                    
  2. Octahedral
  3. Trigonal planer              
  4. Linear
Chapter: [8.01] D-block Elements
Concept: D-block Elements - Some Important Compounds of Transition Elements
[1]5.4

Primary and secondary nitroalcanes containing α - H atom show property of -

  1. chain isomerism
  2. tautomerism
  3. optical isomerism
  4. geometrical isomerism
Chapter: [13.01] Amines
Concept: Amines - Identification of Primary, Secondary and Tertiary Amines
[1]5.5

In phenol carbon atom attached to -OH group undergoes -

  1. SP3 hybridisation          
  2. SP hybridisation
  3. SP2 hybridisation
  4. No hybridisation
Chapter: [11.02] Phenols
Concept: Phenols - Physical and Chemical Properties
[1]5.6

Identify the strongest acid amongst the followings:

  1. Chloroacetic acid          
  2. Acetic acid
  3. Trichloroacetic acid
  4. Dichloroaceticacid
Chapter: [12.02] Carboxylic Acids
Concept: Physical Properties of Carboxylic Acids
[1]5.7

Which of the following vitamins is water soluble?

  1. A
  2. D
  3. E
  4. B
Chapter: [14.03] Vitamins
Concept: Vitamins - Classification of Vitamins
[12]6 | Answer any SIX of the following :
[2]6.1

Write a note on Friedel Craft’s acylation.

Chapter: [10.02] Haloarenes
Concept: Haloarenes - Electrophilic Substitution Reactions
[2]6.2

How is ethyl amine prepared from methyl iodide?

Chapter: [13.01] Amines
Concept: Amines - Preparation of Amines
[2]6.3

What are antibiotics? Give ‘two’ examples

Chapter: [16.01] Chemicals in Medicines
Concept: Drugs and Their Classification
[2]6.4

Explain, why are boiling points of carboxylic acids higher than corresponding alcohols

Chapter: [12.02] Carboxylic Acids
Concept: Physical Properties of Carboxylic Acids
[2]6.5

How are proteins classified on the basis of molecular shapes?

Chapter: [14.02] Proteins
Concept: Proteins - Structure of Proteins
[2]6.6

Explain Interstitial compounds

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

Why do interstitial compounds have higher melting points than corresponding pure metals?

Chapter: [8.01] D-block Elements
Concept: General Properties of the Transition Elements (D-block)
[2]6.7

Write the structures and IUPAC names of the :Adipic acid compound

Chapter: [12.02] Carboxylic Acids
Concept: Carboxylic Acids - Nomenclature

Write the structures and IUPAC names of the α - methyl butyraldehyde.

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Nomenclature
[2]6.8

Explain with examples, branched and linear polymers.

Chapter: [15] Polymers
Concept: Introduction of Polymers
[9]7 | Answer any THREE of the following :
[3]7.1

On the basis of valence bond theory explain the nature of bonding in [CoF6]3 ion.

 

Chapter: [9] Coordination Compounds
Concept: Bonding in Coordination Compounds - Valence Bond Theory (VBT)

Write the IUPAC name of [Co(N02)3(NH3)3].

Chapter: [9] Coordination Compounds
Concept: Nomenclature of Coordination Compounds - Naming of Mononuclear Coordination Compounds
[3]7.2

Define 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

What are the consequences of lanthanoid contraction?

Chapter: [8.02] F-block Elements
Concept: F-block Elements - The Lanthanoids
[3]7.3

Write mechanism of Aldol addition reaction.

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Reactivity of Alpha Hydrogen in Aldehydes
[3]7.4

Define carbohydrates.

Chapter: [14.01] Carbohydrates
Concept: Introduction of Carbohydrates

What are reducing and non-reducing sugars?

Chapter: [14.01] Carbohydrates
Concept: Classification of Carbohydrates
[7]8 | Answer any ONE of the following
[7]8.1

Write a note on Gabriel phthalimide synthesis.

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

What are biodegradable polymers and non-biodegradable polymers? Write ‘one example’ of each.

Chapter: [15] Polymers
Concept: Introduction of Polymers

Explain cationic detergents.

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

How is carbolic acid prepared from the given compounds :

Aniline

Chapter: [11.02] Phenols
Concept: Phenols - Methods of Preparation

How is carbolic acid prepared from the given compounds :

Chlorobenzene and steam at 698K?

Chapter: [11.02] Phenols
Concept: Phenols - Methods of Preparation

Draw structure of DDT.

Chapter: [10.02] Haloarenes
Concept: Polyhalogen Compounds

Write the environmental effects of DDT.

Chapter: [10.02] Haloarenes
Concept: Polyhalogen Compounds

Mention ‘two’ physical properties of carbolic acid.

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