Chemistry 9th Chap 14 : Topic 4 - Maryam Publications

Chemistry Chapter 14 : Topic 4

Photochemical Chlorination

1 / 15

Methane reacts with chlorine in the presence of sunlight. This reaction is best classified as:

A) Substitution reaction

B) Neutralization reaction

C) Polymerization reaction

D) Addition reaction

2 / 15

Which condition is essential for the chlorination of methane to occur?

A) High pressure

B) Nickel catalyst

C) Sunlight / UV light

D) Electric spark

3 / 15

In the reaction CH₃+Cl₂ → CH₃Cl+HCl, the product CH₃Cl is called:

A) Chloromethane

B) Methyl chloride peroxide

C) Methanol

D) Dichloromethane

4 / 15

Which type of mechanism is involved in the chlorination of alkanes?

A) Ionic mechanism

B) Nuclear mechanism

C) Electrolytic mechanism

D) Free radical mechanism

5 / 15

The first step in the photochemical chlorination of methane is:

A) Propagation

B) Initiation

C) Neutralization

D) Termination

6 / 15

Which of the following represents the correct structural change in mono-chlorination of methane?

A) CH₄ → CH₃Cl

B) CH₄ → CCl₄

C) CH₄ → CH₂Cl₂

D) CH₄ → CH₄OH

7 / 15

During propagation in chlorination of methane, which species is regenerated?

A) Chlorine molecule

B) Hydrogen molecule

C) Chlorine radical

D) Methane

8 / 15

Which statement correctly describes free radicals?

A) Highly reactive species with unpaired electrons

B) Charged ions only

C) Stable molecules with full electron shells

D) Molecules with ionic bonds only

9 / 15

What is the role of sunlight in the chlorination of methane?

A) It breaks Cl-Cl bond to form radicals.

B) It acts as a catalyst.

C) It provides pressure.

D) It removes hydrogen atoms directly.

10 / 15

Which of the following correctly shows the products of mono-chlorination of methane?

A) CH₄+Cl₂ → CH₃ Cl+HCl

B) CH₄+Cl₂ → CCl₄+H₂

C) CH₄+Cl₂ → CH₃ OH+HCl

D) CH₄+Cl₂ → CH₂ Cl₂+H₂

11 / 15

Which step involves the formation of a new C-Cl bond in the reaction?

A) First propagation step

B) Termination

C) Initiation

D) Decomposition of methane

12 / 15

Termination step in free radical chlorination occurs when:

A) Methane breaks into ions.

B) UV light is absorbed.

C) Radicals are formed.

D) Radicals are consumed to form stable molecules.

13 / 15

Which structural formula correctly represents chloromethane?

A) H-C-H with two Cl atoms

B) CH₂ Cl₂

C) CH₃-Cl

D) CCl₄

14 / 15

Why is the chlorination of alkanes called a chain reaction?

A) Radicals continuously regenerate during reaction.

B) It requires long carbon chains.

C) It produces only one product.

D) It produces chains of carbon atoms.

15 / 15

Which of the following best describes mono-substitution in alkanes?

A) Addition of chlorine to carbon chain

B) Breaking of carbon backbone

C) Replacement of one hydrogen atom only

D) Replacement of all hydrogen atoms

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