# Chemistry (Theory) Set 1 2017-2018 ISC (Arts) Class 12 Question Paper Solution

Chemistry (Theory) [Set 1]
Date: March 2018

[20]1
[4]1.a
[1]1.a.i

Fill in the blanks by choosing the appropriate word/words from the brackets

(square pyramidal, electrical, 74; 26, sp3d2, sp3d, chemical, 68, 32, tetrahedral, yellow, white, iodoform, Lucas)

A Galvanic cell converts _______ energy into _______ energy.

Concept: Galvanic Cells, Mechanism of Current Production in a Galvanic Cell; - Galvanic Cells - Introduction
Chapter: [6.02] Galvanic cells, mechanism of current production in a galvanic cell;
[1]1.a.ii

Fill in the blanks by choosing the appropriate word/words from the brackets

(square pyramidal, electrical, 74; 26, sp3d2, sp3d, chemical, 68, 32, tetrahedral, yellow, white, iodoform, Lucas)

The percentage of unoccupied spaces in bcc and fcc arrangements are _______ and _____respectively

Concept: States of Matters: Structure and Properties Solid State - Packing in 3 – D
Chapter: [0.02] States of Matters: Structure and Properties Solid State
[1]1.a.iii

Fill in the blanks by choosing the appropriate word/words from the brackets

(square pyramidal, electrical, 74; 26, sp3d2, sp3d, chemical, 68, 32, tetrahedral, yellow, white, iodoform, Lucas)

Propane-2-ol on reaction with iodine and sodium hydroxide gives ________ precipitate and the
reaction is called ___________ test.

Concept: Haloform Reaction for the Preparation of Chloroform and Iodoform from Alcohol Should Be Discussed
Chapter: [11.05] Preparation, properties, and uses of the following
[1]1.a.iv

Fill in the blanks by choosing the appropriate word/words from the brackets

(square pyramidal, electrical, 74; 26, sp3d2, sp3d, chemical, 68, 32, tetrahedral, yellow, white, iodoform, Lucas)

The geometry of XeOF4 molecule is ______ and the hybridisation of Xenon atom in the molecule is ________.

Concept: P - Block Group 18 Elements - Concept of Group 18 Elements
Chapter: [0.08] Chemistry of p-Block Elements: Group 16, 17, 18
[4]1.b | Complete the following statements by selecting the correct alternative from the choices given
[1]1.b.i

During the course of an SN1 reaction, the intermediate species formed is:

(1) a carbocation

(3) a carbanion

(4) an intermediate complex

Concept: Organometallic Compounds - Organometallic Compounds
Chapter: [11.01] Organometallic compounds
[1]1.b.ii

Purification of aluminium by electrolytic refining is carried out by

(a)Hoope process

(b)Hall process

(c)Baeyer process

(d)Serperck process

Concept: Occurrence of Metals
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
[1]1.b.iii

An aqueous solution of urea freezes at – 0.186°C, Kf for water = 1.86 K kg mo1–1, Kb for water = 0.512 K kg mo1–1. The boiling point of urea solution will be:

373.065 K

373.186 K

373.512 K

373.0512 K

Concept: Relative Molecular Mass of Non-volatile Substances - Depression in Freezing Point
Chapter: [1.03] Relative molecular mass of non-volatile substances
[1]1.b.iv

In the dehydration of alcohols to alkenes by heating with concentrated sulphuric acid, the initiation step is:

(1) formation of carbonation

(2) formation of an ester

(3) protonation of the alcohol molecule

(4) elimination of water

Concept: Alcohols, Phenols and Ethers - Nomenclature
Chapter: [12.04] Classification, general formulae, structure and nomenclature [13.02] Ethers
[4]1.c

Match the following

 1 Rate constant a Dialysis 2 Biodegradable polymer b Glycine 3 Zwitterion c Arrhenius equation 4 Purification of colloids d PHBV
Concept: Normality, Molality - Normality, Molality, Molarity, Mole Fraction, as Measures of Concentration
Chapter: [1.05] Normality, molality
[8]1.d | Answer the following questions
[2]1.d.i

Why does the density of transition elements increase from Titanium to Copper? (at. no. Ti = 22,
Cu = 29)

Concept: General Properties of the Transition Elements (D-block)
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series

Account for the following :

Zn is not considered as a transition element.

Concept: General Properties of the Transition Elements (D-block)
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
[2]1.d.ii

Identify the compounds A, B, C and D.

Concept: Carboxylic Acids - Nomenclature
Chapter: [14.01] Carboxylic acids
[2]1.d.iii

Calculate the osmotic pressure of a solution prepared by dissolving 0.025 g of K2SO4 in 2.0 litres of water at 25°C assuming that K2SO4 is completely dissociated. (Mol. wt. of K2SO4 = 174 g mol–1)

Concept: Relative Molecular Mass of Non-volatile Substances - Osmotic Pressure and Its Application in the Determination of Relative Molecular Mass
Chapter: [1.03] Relative molecular mass of non-volatile substances
[2]1.d.iv

What type of isomerism is shown by the following coordination compounds

[PtCl_2(NH_3)_4]Br_2 and [PtBr_2(NH_3)_4]Cl_2

Write their IUPAC names.

Concept: Coordination Compounds - IUPAC rules of nomenclature of coordination compounds
Chapter: [0.07] Coordination Compounds
[2]2 | Attempt Any One
[2]2.a

Write the rate law expression for the reaction A+B+C→D+E, if the order of reaction is first, second and zero with respect to A, B and C, respectively.

Concept: Mechanism of the Reaction - Relationship Between the Rate Expression, Order of Reactants and Products at the Rate- Determining Step
Chapter: [3.03] Mechanism of the reaction

How many times the rate of reaction will increase if the concentration of A, B and C are doubled in the equation given in (i) above?

Concept: Mechanism of the Reaction - Relationship Between the Rate Expression, Order of Reactants and Products at the Rate- Determining Step
Chapter: [3.03] Mechanism of the reaction
[2]2.b

The rate of a reaction quadruples when the temperature changes from 293 K to 313 K. Calculate the energy of activation of the reaction assuming that it does not change with temperature.

Concept: Temperature Dependence of the Rate of a Reaction
Chapter: [3.05] The concept of energy
[2]3
[1]3.a

How do antiseptics differ from disinfectants? Give one example of each.

Concept: Therapeutic Action of Different Classes of Drugs - Antimicrobials
Chapter: [0.18] Chemistry in Everyday Life
[1]3.b

State the role of the following chemicals in the food industry:
(i) Sodium benzoate
(ii) Aspartame

Concept: Ozone - Ozone Depletion in the Stratosphere
Chapter: [0.09] Preparation/ Manufacture, Properties and Uses of Compounds of Groups 16, 17, – Ozone, Sulphur Dioxide, Sulphuric Acid, Hydrochloric Acid
[2]4

An aromatic organic compound [A] on heating with NH3 and Cu2O at high pressure gives [B]. The compound [B] on treatment with the ice-cold solution of NaNO2 and HCI gives [C], which on heating with Cu/HCl gives compound [A] again. Identify the compounds [A], [B] and [C]. Write the name of the reaction for the conversion of [B] to [C].

Concept: Aniline - Sandmeyer’S Reaction
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
[2]5
[1]5.a

Write the name of the monomer of the following polymer:

Bakelite

Concept: Types of Polymerisation Reactions - Condensation Polymerisation Or Step Growth Polymerisation
Chapter: [0.16] Polymers
[1]5.b

Write the name of the monomer of the following polymer:

Nylon – 2 – Nylon – 6

Concept: Types of Polymerisation Reactions - Condensation Polymerisation Or Step Growth Polymerisation
Chapter: [0.16] Polymers
[2]6

Name the purine bases and pyrimidine bases present in RNA and DNA.

Concept: Introduction of Nucleic Acids
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
[2]7
[2]7.a

How will you obtain the following? (Give balanced equation.)
(i) Picric acid from phenol.
(ii) Ethyl chloride from diethyl ether.

Concept: Phenols - Phenols
Chapter: [12.03] Distinction between primary, secondary and tertiary alcohols
OR
[2]7.b

How will you obtain the following? (Give balanced equation.)
(i) Anisole from phenol
(ii) Ethyl acetate from ethanol.

Concept: Phenols - Phenols
Chapter: [12.03] Distinction between primary, secondary and tertiary alcohols
[2]8

40% of a first-order reaction is completed in 50 minutes. How much time will it take for the completion of 80% of this reaction?

Concept: Order of a Reaction - Characteristics of First Order Reaction
Chapter: [3.01] Order of a reaction
[3]9
[3]9.a

The freezing point of a solution containing 5.85 g of NaCl in 100 g of water is -3.348°C. Calculate Van’t Hoff factor ‘i’ for this solution. What will be the experimental molecular weight of NaCl?
(Kf for water = 1.86 K kg mol-1, at. wt. Na = 23, Cl = 35.5)

Concept: Relative Molecular Mass of Non-volatile Substances - Freezing Point Depression
Chapter: [1.03] Relative molecular mass of non-volatile substances
OR
[3]9.b
[3]10

Examine the defective crystal given below and answer the question that follows:

 A+ B- A+ B- A+ B- B- A+ B- A+ B- A+ A+ B- A+ B- A+ B-

State if the above defect is stoichiometric or non-stoichiometric. How does this defect affect the density of the crystal? Also, write the term used for this type of defect.

Concept: States of Matters: Structure and Properties Solid State - Point Defects – F Centers
Chapter: [0.02] States of Matters: Structure and Properties Solid State
[3]11
[1]11.a

Give a Reason of the Following:

For Ferric Hydroxide Sol, the Coagulating Power of Phosphate Ion is More than Chloride Ion.

Concept: Acid Derivatives - Ethyl Acetate Reaction with Phosphorus Penta Chloride
Chapter: [14.02] Acid derivatives
[1]11.b

Give the reason for the following:

Medicines are more effective in their colloidal form.

Concept: Order of a Reaction - Problems Based on First Order Rate Equation and Half Life Period
Chapter: [3.01] Order of a reaction
[1]11.c

Give the reason for the following:

Gelatin is added to ice creams.

Concept: Order of a Reaction - Problems Based on First Order Rate Equation and Half Life Period
Chapter: [3.01] Order of a reaction
[3]12
[1.5]12.a

For the complex ion [Fe(CN)6]3- state:
(i) the type of hybridisation.
(ii) the magnetic behaviour.
(iii) the oxidation number of the central metal atom.

Concept: Potassium Permanganate
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
[1.5]12.b

Write the IUPAC name of [Co(en)2Cl2]+ ion and draw the structures of its geometrical isomers.

Concept: Isomerism in Coordination Compounds - Stereoisomerism
Chapter: [0.07] Coordination Compounds
[3]13
[3]13.a

Explain why:
(i) Mn2+ is more stable than Fe2+ towards oxidation to +3 state.
(At. no. of Mn = 25, Fe = 26)

(ii) Transition elements usually form coloured ions.

(iii) Zr and Hf exhibit similar properties.
(At. no. of Zr = 40, Hf = 72)

Concept: General Properties of the Transition Elements (D-block)
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
OR
[3]13.b

Complete and balance the following chemical equations:

(i) KMnO4 + KI + H2SO4 → ____ + ____ + ____ + _____

(ii) K2Cr2O7 + H2SO4 + H2S → ____ + _____ + _____ + ____

(iii) KMnO4 + H2SO4 + FeSO4 → _____ + _____ + _____ + ____

Concept: Methods of Preparation and Manufacture of Alcohol - Manufacture of Methanol by Bosch Process and Ethanol by Fermentation of Carbohydrates
Chapter: [12.01] Methods of preparation, manufacture, properties and use
[3]14
[1]14.a

Arrange the following in the increasing order of their basic strength:

Concept: Aniline - Physical Properties Anilines
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
[1]14.b

Give a balanced chemical equation to convert methyl cyanide to ethyl alcohol.

Concept: Polyhalogen Compounds
Chapter: [11.04] Chlorobenzene
[1]14.c

What happens when benzene diazonium chloride reacts with phenol in the weak alkaline medium?
(Give a balanced equation).

Concept: Oxalic Acid - Substitution of Benzene Ring (Meta Directive Effect of Carboxylic Acid Group) Nitration and Sulphonation
Chapter: [14.01] Carboxylic acids
[3]15

Name the sulphide ore of Copper. Describe how pure copper is extracted from this ore.

Concept: P - Block Group 16 Elements - Laboratory and Industrial Preparation from Sulphites and Sulphide Ores
Chapter: [0.08] Chemistry of p-Block Elements: Group 16, 17, 18
[5]16
[5]16.a
[2.5]16.a.i

Calculate the emf and ΔG° for the cell reaction at 25°C:

\begin{array}{cl}{\mathrm{Zn}(s) | \mathrm{Zn}_{(a q)}^{2+} \|} & {\mathrm{Cd}_{(a q)}^{2+} | \mathrm{Cd}_{(s)}} \\ \ce{(0 \cdot 1 \mathrm{M})} & \ce{(0 \cdot 01 \mathrm{M})}\end{array}

Given E° Zn2+/Zn = – 0-763 and E°Cd2+/Cd = -0.403

Concept: Concept of Corrosion - Mechanism of Electrochemical Reaction
Chapter: [6.06] Corrosion
[2.5]16.a.ii

Define the following terms:

(1) Equivalent conductivity

(2) Corrosion of metals

Concept: Electrolytic Conductance - Measuring of Molar and Equivalent Conductance
Chapter: [6.04] Electrolytic conductance [6.04] Electrolytic conductance
OR
[5]16.b
[2.5]16.b.i

The specific conductivity of a solution containing 5 g of anhydrous BaCl2 (mol. wt. = 208) in 1000 cm3 of a solution is found to be 0.0058 ohm-1 cm-1. Calculate the molar and equivalent conductivity of the solution.

Concept: Electrolytic Conductance - Measuring of Molar and Equivalent Conductance
Chapter: [6.04] Electrolytic conductance [6.04] Electrolytic conductance
[2.5]16.b.ii

What is an electrochemical series? How is it useful in predicting whether a metal can liberate hydrogen from acid or not?

Concept: Galvanic Cells, Mechanism of Current Production in a Galvanic Cell; - Electrochemical Series
Chapter: [6.02] Galvanic cells, mechanism of current production in a galvanic cell;
[5]17
[5]17.a
[2.5]17.a.i

Explain why:

(1) Nitrogen does not form pentahalides.

(2) Helium is used for filling weather balloons.

(3) ICl is more reactive than I2.

Concept: Reversible Reactions and Dynamic Equilibrium - The Dissociation of Dinitrogen Tetra Oxide
Chapter: [4.01] Reversible reactions and dynamic equilibrium
[2.5]17.a.ii

Draw the structures of the following:
(1) HClO4
(2) H3PO3

Concept: P - Block Group 17 Elements - Oxoacids of Halogens
Chapter: [0.08] Chemistry of p-Block Elements: Group 16, 17, 18
OR
[5]17.b
[2.5]17.b.i

Explain why:
(1) Mercury loses its meniscus in contact with ozone.

(2) Halogens are coloured and the colour deepens on moving down in the group from fluorine to iodine.

(3) Hydride of sulphur is a gas while hydride of oxygen is a liquid.

Concept: Ozone - Reaction with Lead Sulphide, Potassium Iodide and Mercury
Chapter: [0.09] Preparation/ Manufacture, Properties and Uses of Compounds of Groups 16, 17, – Ozone, Sulphur Dioxide, Sulphuric Acid, Hydrochloric Acid
[2.5]17.c

Complete and balance the following reactions:

(1) NaCl + MnO2 + H2SO4 → _____ + _____ + ______ + _____

(2) KMnO4 + SO2 + H2O → _____ + ______ + ______ + ______

Concept: Stability of Coordination Compounds
Chapter: [0.07] Coordination Compounds
[5]18
[5]18.a
[2.5]18.a.i

Give balanced equations for the following reactions:

(1) Benzaldehyde reacts with hydrazine.

(2) Acetic acid reacts with phosphorous pentachloride.

(3) Acetone reacts with sodium bisulphite.

Concept: Aldehydes and Ketones - Chemical Properties of Benzaldehyde
Chapter: [13.01] Carbonyl compounds
[2.5]18.a.ii

Give one chemical test each to distinguish between the following pairs of compounds:

(1) Ethanol and acetic acid

(2) Acetaldehyde and benzaldehyde

Concept: Ionic Equilibria - Common Ion Effect Example
Chapter: [5.07] Common ion effect
OR
[5]18.b
[2.5]18.b.i

Write chemical equations to illustrate the following name reactions:

(1) Clemmensen’s reduction

(2) Rosenmund’s reduction

(3) HVZ reaction

Concept: Aldehydes and Ketones - Reduction to Alcohol and Alkanes
Chapter: [13.01] Carbonyl compounds
[2.5]18.b.ii

Explain why:

(1) Acetaldehyde undergoes aldol condensation but formaldehyde does not.

(2) Acetic acid is a weaker acid as compared to formic acid.

Concept: Ionic Equilibria - Common Ion Effect Example
Chapter: [5.07] Common ion effect

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