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Question Paper Solutions - Chemistry 2015 - 2016-CBSE 12th-Class 12 CBSE (Central Board of Secondary Education)

Alternate Sets

    

Marks: 70
[1]1

Write the IUPAC name of the given compound:

 

Chapter: [9] Coordination Compounds
Concept: Nomenclature of Coordination Compounds - Naming of Mononuclear Coordination Compounds
[1]2

Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction

Chapter: [10.01] Haloalkanes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloalkanes - Nucleophilic Substitution Reactions
[1]3

What is the reason for the stability of colloidal sols?

Chapter: [5] Surface Chemistry
Concept: Properties of Colloidal Solutions
[1]4

Give an example each of a molecular solid and an ionic solid.

Chapter: [1] Solid State
Concept: Classification of Crystalline Solids
[1]5

Pb(NO3)2 on heating gives a brown gas which undergoes dimerisation on cooling? Identify the gas

Chapter: [7] P - Block Elements
Concept: P - Block Group 15 Elements - Oxides of Nitrogen
[2]6

For a reaction: 

Rate = k

(i) Write the order and molecularity of this reaction.

(ii) Write the unit of k.

Chapter: [5] Chemical Kinetics
Concept: Factors Influencing Rate of a Reaction
[2]7

Write the chemical equations involved in the following reactions:(i) Hoffmann-bromamide degradation reaction

Chapter: [15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
Concept: Amines - Preparation of Amines

Write the chemical equations involved in the following reactions: Carbylamine reaction

Chapter: [13.01] Amines
Concept: Amines - Chemical Reactions of Amines - Carbylamine Reaction
[2]8

Gas (A) is more soluble in water than Gas (B) at the same temperature. Which one of the two gases will have the higher value of KH (Henry’s constant) and why

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

In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes?

Chapter: [2] Solutions
Concept: Vapour Pressure of Liquid Solutions - Vapour Pressure of Liquid- Liquid Solutions
[2]9

When a coordination compound CoCl3.6NH3 is mixed with AgNO3, 3moles of AgCl are precipitated per mole of the compound. Write

(i) Structural formula of the complex

Chapter: [7] Coordination Compounds
Concept: Isomerism in Coordination Compounds - Stereoisomerism

When a coordination compound CoCl3.6NH3 is mixed with AgNO3, 3moles of AgCl are precipitated per mole of the compound. Write (ii) IUPAC name of the complex

Chapter: [9] Coordination Compounds
Concept: Nomenclature of Coordination Compounds - Naming of Mononuclear Coordination Compounds
[2]10 | Attempt Any One
[2]10.1

Draw the structures of the following molecules: BrF3

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: P - Block Group 17 Elements - Interhalogen Compounds

Draw the structures of the following molecules: XeF4

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: P - Block Group 18 Elements - Concept of Group 18 Elements
[2]10.2

What happens when: SO2 gas is passed through an aqueous solution Fe+3 salt?

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: P - Block Group 16 Elements - Sulphur Dioxide

What happens when: XeF4 reacts with SbF5?

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: P - Block Group 18 Elements - Concept of Group 18 Elements
[3]11

Write the final product(s) in each of the following reactions:

Chapter: [10.02] Haloarenes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloarenes - Nucleophilic Substitution

Write the final product(s) in each of the following reactions:

Chapter: [11] Alcohols, Phenols and Ethers
Concept: Chemical Reactions of Alcohols and Phenols - Reactions Involving Cleavage of Carbon–Oxygen (C–O) Bond in Alcohols

Write the final product(s) in each of the following reactions:

 

Chapter: [12.05] Distinction between primary, secondary and tertiary alcohols
Concept: Chemical Reactions of Phenols (Only)
[3]12 | Attempt Any One
[3]12.1

How do you convert: Chlorobenzene to biphenyl

Chapter: [10.01] Haloalkanes
Concept: Introduction of Haloalkanes and Haloarenes

How do you convert: Propene to 1-iodopropane

Chapter: [10] Haloalkanes and Haloarenes
Concept: Methods of Preparation of Haloalkanes and Haloarenes

How do you convert: 2-bromobutane to but-2-ene

Chapter: [10.01] Haloalkanes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloalkanes - Elimination Reactions
[3]12.2

Write the major products(s) in the following:

Chapter: [13] Organic Compounds Containing Nitrogen
Concept: Diazonium Salts - Importance of Diazonium Salts in Synthesis of Aromatic Compounds

Write the major products(s) in the following:

Chapter: [10] Haloalkanes and Haloarenes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloarenes - Reaction with Metals

Write the major products(s) in the following:

Chapter: [10.01] Haloalkanes
Concept: Chemical Reactions of Haloalkanes and Haloarenes - Reactions of Haloalkanes - Nucleophilic Substitution Reactions
[3]13

Write the structural difference between starch and cellulose.

Chapter: [14.01] Carbohydrates
Concept: Carbohydrates - Polysaccharides

What type of linkage is present in nucleic acids?

Chapter: [14] Biomolecules
Concept: Introduction of Nucleic Acids

Give one example each for fibrous protein and globular protein.

Chapter: [17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
Concept: Introduction of Proteins
[3]14

Name the method used for the refining of Nickel metal.

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

What is the role of cryolite in the extraction of aluminium?

Chapter: [10] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Concept: Occurrence of Metals

What is the role of limestone in the extraction of iron from its oxides?

Chapter: [10] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Concept: Occurrence of Metals
[3]15

Give reasons: SO2 is reducing while TeO2 is an oxidising agent.

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: Concept of Group 16 Elements

Nitrogen does not form pentahalide.

Chapter: [7.01] Group 15 Elements
Concept: Concept of Group 15 Elements

ICl is more reactive than I2.

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: P - Block Group 17 Elements - Interhalogen Compounds
[3]16

For the complex [Fe(H2O)6]+3, write the hybridisation, magnetic character and spin of the complex. (At, number : Fe = 26)

Chapter: [9] Coordination Compounds
Concept: Bonding in Coordination Compounds - Magnetic Properties of Coordination Compounds

Draw one of the geometrical isomers of the complex [Pt (en)2Cl2] +2 which is optically inactive

Chapter: [7] Coordination Compounds
Concept: Isomerism in Coordination Compounds - Stereoisomerism
[3]17

An element crystallises in a b.c.c lattice with cell edge of 500 pm. The density of the element is 7.5g cm-3. How many atoms are present in 300 g of the element?

Chapter: [1] Solid State
Concept: Number of Atoms in a Unit Cell
[3]18

What is the role of sulphur in the vulcanisation of rubber?

Chapter: [16] Polymers
Concept: Types of Polymerisation Reactions - Rubber

Identify the monomers in the following polymer:

Chapter: [15] Polymers
Concept: Introduction of Polymers

Arrange the following polymers in the Increasing order of their intermolecular forces:

Terylene, Polythene, Neoprene

Chapter: [15] Polymers
Concept: Introduction of Polymers
[3]19

For the first order thermal decomposition reaction, the following data were obtained:

Time / sec               Totalpressure / atm

0                              0.30

300                          0.50

Calculate the rate constant

(Given: log 2 = 0.301, log3 = 0.4771, log 4 = 0.6021)

Chapter: [5] Chemical Kinetics
Concept: Factors Influencing Rate of a Reaction
[3]20

Give reasons for the following:

Aniline does not undergo Friedal- Crafts reaction.

Chapter: [15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
Concept: Amines - Chemical Reactions of Amines - Electrophilic Substitution

Give reasons for the following: (CH3)2NH is more basic than (CH3)3N in an aqueous solution.

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

Give reasons for the following: Primary amines have higher boiling point than tertiary amines.

Chapter: [13.01] Amines
Concept: Physical Properties of Amines
[3]21

Define the following terms: Lyophilic colloid

Chapter: [5] Surface Chemistry
Concept: Classification of Colloids - Classification Based on Nature of Interaction Between Dispersed Phase and Dispersion Medium

Define the following terms: Zeta potential

Chapter: [5] Surface Chemistry
Concept: Catalysis - Enzyme Catalysis

Define the following terms: Associated colloids

Chapter: [5] Surface Chemistry
Concept: Properties of Colloidal Solutions
[3]22

Calculate the boiling point of solution when 4g of MgSO4 (M= 120 g mol-1) was dissolved in 100g of water, assuming MgSO4 undergoes complete ionization. (Kb for water = 0.52 K kgmol-1)

Chapter: [2] Solutions and Colligative Properties
Concept: Colligative Properties and Determination of Molar Mass - Elevation of Boiling Point
[4]23

Due to hectic and busy schedule, Mr Angad made his life full of tensions and anxiety. He started taking sleeping pills to overcome the depression without consulting the doctor. Mr Deepak, a close friend of Mr. Angad advised him to stop taking sleeping pills and suggested to change his life lifestyle by doing yoga, meditation and some physical exercise. Mr. Angad followed his friend’s advice and after few days he started feeling better.

After reading the above passage, answer the following

(i) What are the values (at least two) displayed by Mr. Deepak?

(ii) Why is it not advisable to take sleeping pills without consulting doctor?

(iii) What are tranquilisers? Give two examples.

Chapter: [16.01] Chemicals in Medicines
Concept: Drugs and Their Classification
[5]24 | Attempt Any One
[5]24.1

Write the structures of A and B in the following reactions:

Chapter: [12.01] Aldehydes and Ketones
Concept: Aldehydes and Ketones - Preparation of Aldehydes and Ketones

Write the structures of A and B in the following reactions

Chapter: [14.01] Carboxylic acids
Concept: Carboxylic Acids - Methods of Preparation of Carboxylic Acids

Distinguish between:

C6H5-COCH3 and C6H5-CHO

Chapter: [12] Aldehydes, Ketones and Carboxylic Acids
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Oxidation

Distinguish between: CH3COOH and HCOOH

Chapter: [12] Aldehydes, Ketones and Carboxylic Acids
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Oxidation

Arrange the following in the increasing order of their boiling points: CH3CHO, CH3COOH, CH3CH2OH

Chapter: [12.01] Aldehydes and Ketones
Concept: Physical Properties of Aldehydes and Ketones
[5]24.2

Write the chemical reaction involved in Wolff-Kishner reduction.

Chapter: [12] Aldehydes, Ketones and Carboxylic Acids
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Reduction

Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction:

C6H5COCH3, CH3-CHO, CH3COCH3

Chapter: [12] Aldehydes, Ketones and Carboxylic Acids
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Nucleophilic Addition Reactions

Why carboxylic acid does not give reactions of carbonyl group?

Chapter: [12.02] Carboxylic Acids
Concept: Carboxylic Acids - Structure of the Carboxyl group

Write the product in the following reaction

Chapter: [14.02] Acid derivatives
Concept: Aldehydes and Ketones - Preparation of Aldehydes

A and B are two functional isomers of compound C3H6O.On heating with NaOH and I2, isomer B forms yellow precipitate of iodoform whereas isomer A does not form any precipitate. Write the formulae of A and B.

Chapter: [12] Aldehydes, Ketones and Carboxylic Acids
Concept: Aldehydes and Ketones - Chemical Reactions of Aldehydes and Ketones - Oxidation
[5]25 | Attempt Any One
[5]25.1

Calculate E°cell for the following reaction at 298K:

2Al(s) + 3Cu+2(0.01M) → 2Al+3(0.01M) + 3Cu(s)

Given: Ecell = 1.98V

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

Using the E° values of A and B, predict which is better for coating the surface of iron [E°(Fe+2/Fe) = -0.44V] to prevent corrosion and why?

Given: E° (A+2/A)=-2.37 V: E°(B+2/B)= -0.14V

Chapter: [3] Electrochemistry
Concept: Electrolytic Cells and Electrolysis - Introduction
[5]25.2

The conductivity of 0.001 mol L-1 solution of CH3COOH is 3.905× 10-5 S cm-1. Calculate its molar conductivity and degree of dissociation (α) Given λ°(H+)= 349.6 S cm2 mol-1 and λ°(CH3COO)= 40.9S cm2mol-1.

Chapter: [6.04] Electrolytic conductance
Concept: Conductance of Electrolytic Solutions - Variation of Conductivity and Molar Conductivity with Concentration

Define electrochemical cell

Chapter: [6.03] Galvanic cells, mechanism of current production in a galvanic cell;
Concept: Batteries - Primary Batteries

What happens if external potential applied becomes greater than E°cell of electrochemical cell?

Chapter: [4] Electrochemistry
Concept: Galvanic Cells - Introduction
[5]26 | Attempt Any One
[5]26.1

Account for the following:

Mn shows the highest oxidation state of +7 with oxygen but with fluorine, it shows oxidation state of +4.

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)

Account for the following: Cr+2 is a strong reducing agent

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)

Account for the following:

Cu+2 salts are coloured, while Zn+2 salts are white.

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)

Complete the following equations:

Chapter: [8] "D" and "F" Block Elements
Concept: Some Important Compounds of Transition Elements - Oxides and Oxoanions of Metals

Complete the following equations: Cr2O72- + 14H+ + 6I →

Chapter: [8] "D" and "F" Block Elements
Concept: Some Important Compounds of Transition Elements - Oxides and Oxoanions of Metals
[5]26.2

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Write the element which shows maximum number of oxidation states. Give reason.

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Which element has the highest m.p?

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Which element shows only +3 oxidation state?

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)

The elements of 3d transition series are given as: Sc Ti V Cr Mn Fe Co

Answer the following: Which element is a strong oxidising agent in +3 oxidation state and why?

Chapter: [8] "D" and "F" Block Elements
Concept: General Properties of the Transition Elements (D-block)
S