Class 12 ISC term2 Chemistry Specimen 2022

Section-A [Chemistry Specimen Paper Semester-2 2022]

Question 1

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)

(i) 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 __________.

Solution

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

Solution

(iii) Calcium formate on distillation gives ___________ but the distillation of calcium formate and calcium acetate gives ___________.

Solution

Question 2

Select and write the correct alternative from the choices given below

(i) The type of hybridization involved in Octahedral complexes is:

1. sp³
2. dsp²
3. sp³d
4. d²sp³

Solution

(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:

1. ethene
2. propene
3. 1-butene
4. 2-butene

Solution

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

1. cyanides
2. isocyanides
3. benzene diazonium chloride
4. secondary amines

Solution

(iv) Assertion: The conversion of fresh precipitate to colloidal state is called peptization.
Reason: It is caused by addition of common ions.

1. Both assertion and reason are true and reason is the correct explanation of assertion
2. Both assertion and reason are true but reason is not the correct explanation for assertion.
3. Assertion is true but reason is false
4. Assertion is false but reason is true.

Solution

Section-B

Question 3

Name the type of isomerism shown by each of the following pairs of compounds:

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

Solution

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

Solution

Question 4

(i) Write chemical equations to illustrate each of the following name reactions:

1. Rosenmund’s reduction

Solution


2. Clemmensen’s reduction

Solution

OR

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

1. Acetic acid to acetone

Solution


2. Formaldehyde to urotropine

Solution

Question 5

What is a zwitter ion? Represent the zwitter ion of glycine.

Solution

Question 6

1. Arrange the following in the increasing order of their basic strength: C₂H₅NH₂, C₆H₅NH₂, (C₂H₅)₂NH.

Solution


2. What are the products formed when benzene diazonium chloride reacts with phenol in weak alkaline medium? (Give equation).

Solution

Question 7

Give reasons for the following:

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

Solution


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

Solution

Question 8

The rate of reaction becomes four times when the temperature changes from 293K to 313K. Calculate the energy of activation (E_a) of the reaction assuming that it does not change with temperature. (R = 8·314 JK^-1mol^-1 )

Solution

Question 9

Give balanced equation for each of the following:

(i) Ethylamine and nitrous acid

Solution

(i) Aniline and acetyl chloride

Solution

Question 10

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

(i) Acetaldehyde and benzaldehyde

Solution

(ii) Acetone and acetic acid

Solution

Section-C

Question 1

Answer the following:

(a) Define molecularity of a reaction. Give one difference between the order of reaction and its molecularity

Solution

(b) The rate constant (k) of a first order reaction is 4·5 x 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?

Solution

OR

Answer the following:

(a) For a first order reaction, show that the time required for the completion of 99% reaction is twice the time required for the completion of 90% of the reaction.

Solution

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

Solution

Question 12

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

Solution

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

Solution

Question 13

(i) Write the formula of each of the following compounds:

1. Potassium trioxalatoaluminate (III)
2. Triammine triaquachromium (III) chloride

Solution

(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.

Solution

Question 14

(i) For ferric hydroxide sol. the coagulating power of phosphate ion is more than chloride ion

Solution

(ii) Lyophilic colloidal specimenchapimg/isc-chem-speci are more stable than lyophobic colloidal specimenchapimg/isc-chem-speci.

Solution

(iii) Gelatin is added to ice cream.

Solution