Chemistry (Theory) Set 1 2021-2022 ISC (Commerce) Class 12 Question Paper Solution

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Chemistry (Theory) [Set 1]
Marks: 35 CISCE
ISC (Commerce)
ISC (Arts)
ISC (Science)

Academic Year: 2021-2022
Date: April 2022
Duration: 1h30m
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Note :

  1.  Candidates are allowed an additional 10 minutes for only reading the paper.
  2. They must NOT start writing during this time.
  3. All Questions are compulsory.
  4. The intended marks or parts of questions are given in brackets. [ ]
  5. All working, including rough work, should be done on the same sheet as, and adjacent to the rest of the answer.
  6. Balanced equations must be given wherever possible and diagrams where they are helpful.
  7. When solving numerical problems, all essential work must be shown.
    In working out problems, use the following data:
    Gas constant R = 1⋅987 deg-1 K-1 mol-1 = 8·314 JK-1 mol-1 = 0·0821 dm3 atm K-1 mol-1 1 l atm = 1 dm3 atm = 101⋅3 J. 1 Faraday = 96500 coulombs.
    Avogadro's number = 6·023 ·1023.

SECTION - A
[3]1 | Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:
[1]1.i

Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:

(two, four, sec-1, diamagnetic, acetaldehyde, mol-1L sec-1, paramagnetic, formaldehyde, acetone, ethanol)

When the concentration of a reactant of first-order reaction is doubled, the rate of reaction becomes ______ times. The unit of rate constant (k) for the first-order reaction is ______.

Concept: Order of a Reaction - Characteristics of First Order Reaction
Chapter: [0.0301] Order of a reaction
[1]1.ii

Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:

(two, four, sec-1, diamagnetic, acetaldehyde, mol-1L sec-1, paramagnetic, formaldehyde, acetone, ethanol)

The transition metals show ______ character because of the presence of unpaired electrons while Cu+ is ______ because its electronic configuration is [Ar]3d10.

Concept: Chemistry of Transition and Inner-transition Elements: D-block: 3d, 4d and 5d Series - D-block: 3d, 4d and 5d Series
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.iii

Fill in the blanks by choosing the appropriate word(s) from those given in the brackets:

(two, four, sec-1, diamagnetic, acetaldehyde, mol-1L sec-1, paramagnetic, formaldehyde, acetone, ethanol)

Calcium formate on distillation gives ______ but the distillation of calcium formate and calcium acetate gives ______.

Concept: Aldehydes and Ketones - Difference Between Formaldehyde and Acetaldehyde
Chapter: [0.131] Carbonyl compounds
[4]2 | Select and write the correct alternative from the choices given below.
[1]2.i

The type of hybridization involved in Octahedral complexes is ______.

sp3

dsp2

sp3d

d2sp3

Concept: Bonding in Coordination Compounds - Valence Bond Theory (VBT)
Chapter: [0.07] Coordination Compounds
[1]2.ii

One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 amu. The alkene is:

ethene

propene

1-butene

2-butene

Concept: Aldehydes and Ketones - Preparation of Aldehydes and Ketones from Alkenes (Ozonolysis)
Chapter: [0.131] Carbonyl compounds
[1]2.iii

Primary amine when warmed with chloroform and alc. KOH yields:

cyanides

isocyanides

benzene diazonium chloride

secondary amines

Concept: Isocyanides - Methods of preparation From primary amines
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
[1]2.iv

Assertion: The conversion of fresh precipitate to colloidal state is called peptization.

Reason: It is caused by addition of common ions.

Both assertion and reason are true and reason is the correct explanation of assertion.

Both assertion and reason are true but reason is not the correct explanation for assertion.

Assertion is true but reason is false.

Assertion is false but reason is true.

Concept: Colloidal State
Chapter: [0.19] Surface Chemistry
SECTION - B
[2]3
[1]3.i

Name the type of isomerism shown by the following pair of compounds:

[CoCl(H2O)(NH3)4]Cl2 and [CoCl2(NH3)4]Cl.H2O

Concept: Isomerism in Coordination Compounds - Stereoisomerism
Chapter: [0.07] Coordination Compounds
[1]3.ii

Name the type of isomerism shown by the following pair of compounds:

[Cr(NH3)5Br]SO4 and [Cr(NH3)5SO4]Br

Concept: Isomerism in Coordination Compounds - Stereoisomerism
Chapter: [0.07] Coordination Compounds
[2]4
[2]4.i
[1]4.i.a

Write a chemical equation to illustrate the following name reaction:

Rosenmund’s reduction

Concept: Aldehydes and Ketones - Preparation of Aldehydes and Ketones From acid chlorides
Chapter: [0.131] Carbonyl compounds
[1]4.i.b

Give a balanced equation for the following name reaction:

Clemmensen’s reduction.

Concept: Aldehydes and Ketones - Reduction to Alcohol and Alkanes
Chapter: [0.131] Carbonyl compounds
OR
[2]4.ii
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[1]4.ii.a

How will you bring about the following conversion? (Give equation).

Acetic acid to acetone

Concept: Acids - Tests for Acids: Formic Acid and Acetic Acid
Chapter: [0.141] Carboxylic acids
[1]4.ii.b

How will you bring about the following conversion? (Give equation).

Formaldehyde to urotropine

Concept: Aldehydes and Ketones - Difference Between Formaldehyde and Acetaldehyde
Chapter: [0.131] Carbonyl compounds
[2]5

What is a zwitter ion?

Concept: Proteins - Classification and Zwitter Ion Formation
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids

Represent the zwitter ion of glycine.

Concept: Proteins - Classification and Zwitter Ion Formation
Chapter: [0.17] Biomolecules – carbohydrates, proteins, enzymes, vitamins and nucleic acids
[2]6
[1]6.i

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

C2H5NH2, C6H5NH2, (C2H5)2NH

Concept: Classification of Amines
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
[1]6.ii

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: [0.141] Carboxylic acids
[2]7
[1]7.i

Give reason for the following:

Diabetic patients are advised to take artificial sweeteners instead of natural sweeteners.

Concept: Chemicals in Food
Chapter: [0.18] Chemistry in Everyday Life
[1]7.ii

Give reason for the following:

The use of aspartame is limited to cold foods and drinks.

Concept: Chemicals in Food
Chapter: [0.18] Chemistry in Everyday Life
[2]8

The rate of reaction becomes four times when the temperature changes from 293 K to 313 K. Calculate the energy of activation (Ea) of the reaction assuming that it does not change with temperature. (R = 8.314 JK-1 mol-1)

Concept: Effect of Temperature on the Rate Constant of a Reaction - Numerical Based on Arrhenius Equation
Chapter: [0.0304] Effect of temperature on the rate constant of a reaction
[2]9
[1]9.i

Give the balanced equation for the following:

Ethylamine and nitrous acid

Concept: Amines - Chemical Reactions of Amines - Reaction with Nitrous Acid
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
[1]9.ii

Give the balanced equation for the following:

Aniline and acetyl chloride

Concept: Anline Reaction with HCl and H2so4
Chapter: [0.15] Cyanides, Isocyanides, Nitro compounds, Amines and Diazonium Salt
[2]10
[1]10.i

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

Acetaldehyde and benzaldehyde

Concept: Uses of Aldehydes and Ketones
Chapter: [0.131] Carbonyl compounds
[1]10.ii

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

Acetone and acetic acid

Concept: Acids - Tests for Acids: Formic Acid and Acetic Acid
Chapter: [0.141] Carboxylic acids
SECTION - C
[3]11 | Answer the following:
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[3]11.i
[1.5]11.i.a

Define molecularity of a reaction.

Concept: Chemical Kinetics - Molecularity of the Reaction
Chapter: [0.0311] Molecularity of the reaction

Give one difference between the order of reaction and its molecularity.

Concept: Mechanism of the Reaction - Relationship Between the Rate Expression, Order of Reactants and Products at the Rate- Determining Step
Chapter: [0.030299999999999997] Mechanism of the reaction
[1.5]11.i.b

The rate constant (k) of a first-order reaction is 4.5 × 10-2 sec-1. What will be the time required for the initial concentration of 0.4 M of the reactant to be reduced to 0.2 M?

Concept: Mechanism of the Reaction - Relationship Between the Rate Expression, Order of Reactants and Products at the Rate- Determining Step
Chapter: [0.030299999999999997] Mechanism of the reaction
OR
[3]11.ii | Answer the following:
[1.5]11.ii.a

Show that the time required for 99% completion is double of the time required for the completion of 90% reaction.

Concept: Half Life Period of a Reaction
Chapter:
[1.5]11.ii.b

For a reaction, rate = k[A]1 [B]1.5 [C]0. What is the overall order of reaction?

Concept: Dependence of Rate on Reactant Concentrations: Rate Law and Rate Constant - General rate equation
Chapter: [0.031] Effect of concentration of reactants on the rate of a reaction
[3]12
[1.5]12.i

What is the basic difference between the electronic configuration of transition and inner transition elements?

Concept: Chemistry of Transition and Inner-transition Elements: F-block: 4f and 5f Series - F-block: 4f and 5f Series
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.ii

Why are Zn2+ ions colourless while Ni2+ ions are green in colour?

Concept: Chemistry of Transition and Inner-transition Elements: D-block: 3d, 4d and 5d Series - D-block: 3d, 4d and 5d Series
Chapter: [0.1] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
[3]13
[1.5]13.i
[0.75]13.i.a

Using IUPAC norms write the formulae for Potassium trioxalatoaluminate(III)

Concept: Importance and Applications of Coordination Compounds
Chapter: [0.07] Coordination Compounds
[0.75]13.i.b

Write the formula of the following compound:

Triammine triaquachromium (III) chloride

Concept: Polyhalogen Compounds
Chapter: [0.114] Chlorobenzene
[1.5]13.ii

For the complex ion [Co(NH3)6]3+, state the oxidation state of central metal atom and the coordination number of the complex ion.

Concept: Coordination Compounds - Study of Oxidation State of an Element in a Complex
Chapter: [0.07] Coordination Compounds
[3]14
[1]14.i

Give a Reason for 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: [0.142] Acid derivatives
[1]14.ii

Give reason for the following:

Lyophilic colloidal solutions are more stable than lyophobic colloidal solutions.

Concept: Properties of Colloidal Solutions
Chapter: [0.19] Surface Chemistry
[1]14.iii

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: [0.0301] Order of a reaction

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