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# Question Paper Solutions for Chemistry (Theory) Set A 2017-2018 ISC (Commerce) Class 12

SubjectChemistry (Theory)
Year2017 - 2018 (March)

Marks: 70
[20]1
[4]1.1
[1]1.1.1

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.

Chapter: [6.03] Galvanic cells, mechanism of current production in a galvanic cell;
Concept: Galvanic Cells, Mechanism of Current Production in a Galvanic Cell; - Galvanic Cells - Introduction
[1]1.1.2

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

Chapter: [2] States of Matters: Structure and Properties Solid State
Concept: States of Matters: Structure and Properties Solid State - Packing in 3 – D
[1]1.1.3

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.

Chapter: [11.03] Preparation, properties, and uses of the following
Concept: Haloform Reaction for the Preparation of Chloroform and Iodoform from Alcohol Should Be Discussed
[1]1.1.4

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 ________.

Chapter: [8] Chemistry of p-Block Elements: Group 16, 17, 18
Concept: P - Block Group 18 Elements - Concept of Group 18 Elements
[4]1.2 | Complete the following statements by selecting the correct alternative from the choices given
[1]1.2.1

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

(1) a carbocation

(3) a carbanion

(4) an intermediate complex

Chapter: [11.05] Organometallic compounds
Concept: Organometallic Compounds - Organometallic Compounds
[1]1.2.2

Purification of aluminium by electrolytic refining is carried out by

(a)Hoope process

(b)Hall process

(c)Baeyer process

(d)Serperck process

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
[1]1.2.3

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:

(1) 373.065 K

(2) 373.186 K

(3) 373.512 K

(4) 373.0512 K

Chapter: [1.06] Relative molecular mass of non-volatile substances
Concept: Relative Molecular Mass of Non-volatile Substances - Depression in Freezing Point
[1]1.2.4

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

Chapter: [12.01] Classification, general formulae, structure and nomenclature
Concept: Alcohols, Phenols and Ethers - Nomenclature

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

Chapter: [13.01] Ethers
Concept: Alcohols, Phenols and Ethers - Nomenclature
[4]1.3

Match the following

 1 Rate constant a Dialysis 2 Biodegradable polymer b Glycine 3 Zwitterion c Arrhenius equation 4 Purification of colloids d PHBV
Chapter: [1.01] Normality, molality
Concept: Normality, Molality - Normality, Molality, Molarity, Mole Fraction, as Measures of Concentration
[8]1.4 | Answer the following questions
[2]1.4.1

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

Chapter: [10] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Concept: General Properties of the Transition Elements (D-block)

Account for the following :

Zn is not considered as a transition element.

Chapter: [10] Chemistry of Transition and Inner-Transition Elements: d-Block: 3d, 4d and 5d series f-Block: 4f and 5f series
Concept: General Properties of the Transition Elements (D-block)
[2]1.4.2

Identify the compounds A, B, C and D.

Chapter: [14.01] Carboxylic acids
Concept: Carboxylic Acids - Nomenclature
[2]1.4.3

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)

Chapter: [1.06] Relative molecular mass of non-volatile substances
Concept: Relative Molecular Mass of Non-volatile Substances - Osmotic Pressure and Its Application in the Determination of Relative Molecular Mass
[2]1.4.4

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.

Chapter: [7] Coordination Compounds
Concept: Coordination Compounds - IUPAC rules of nomenclature of coordination compounds
[2]2 | Attempt Any One
[2]2.1

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.

Chapter: [3.09] Mechanism of the reaction
Concept: Mechanism of the Reaction - Relationship Between the Rate Expression, Order of Reactants and Products at the Rate- Determining Step

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?

Chapter: [3.09] Mechanism of the reaction
Concept: Mechanism of the Reaction - Relationship Between the Rate Expression, Order of Reactants and Products at the Rate- Determining Step
[2]2.2

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.

Chapter: [3.06] The concept of energy
Concept: Temperature Dependence of the Rate of a Reaction
[2]3
[1]3.1
[1]3.2
[1]3.3
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