Chemistry 9th Chap 14 : Topic 5 - Maryam Publications

Chemistry Chapter 14 : Topic 5

Preparation of Alkanes

1 / 23

Which statement best explains cracking of alkanes in petroleum refining?

A) Breaking of large hydrocarbons into smaller alkanes and alkenes using heat / catalyst

B) Conversion of alkanes into alcohols using acids

C) Formation of alkanes by combining hydrogen with oxygen

D) Conversion of small alkanes into larger hydrocarbons using pressure

2 / 23

Which equation correctly represents cracking of decane?

A) C₁₀ H₂₂+H₂ → C₁₀ H₂₄

B) C₁₀ H₂₂ → C₁₀ H₂₂

C) C₁₀ H₂₂ → C₅ H₁₂+C₅ H₁₀

D) C₅ H₁₂ → C₁₀ H₂₂

3 / 23

Hydrogenation of ethene produces which product?

A) Ethyne

B) Methane

C) Ethanol

D) Ethane

4 / 23

Which condition is necessary for hydrogenation of alkenes?

A) Nickel or platinum catalyst with hydrogen gas

B) High pressure oxygen

C) Acidic medium

D) Sunlight only

5 / 23

What is the product of complete hydrogenation of ethyne?

A) Ethane

B) Ethene

C) Methane

D) Ethanol

6 / 23

Which equation shows hydrogenation of ethyne?

A) C₂H₂+O₂ → CO₂+H₂O

B) C₂H₂+H₂ → C₂H₄

C) C₂H₂+2H₂ → C₂H₆

D) C₂H₂ → C₂H₆+H₂

7 / 23

Alkyl halides can be converted into alkanes by:

A) Polymerization

B) Hydrolysis only

C) Oxidation

D) Reduction

8 / 23

Which equation represents reduction of chloroethane?

A) C₂H₅Cl+O₂ → CO₂+H₂O

B) C₂H₅Cl → C₂H₄+HCl

C) C₂H₅Cl+H₂ → C₂H₆+HCl

D) C₂H₆ → C₂H₅Cl H₂

9 / 23

Cracking is important because it:

A) Produces only gases

B) Converts all hydrocarbons into alcohols

C) Removes hydrogen from compounds

D) Increases yield of useful fuels like petrol

10 / 23

Which pair is always produced in cracking?

A) Alkane and alcohol

B) Alkane and acid

C) Alkane and alkene

D) Alkene and ketone

11 / 23

Hydrogenation is classified as:

A) Addition reaction

B) Substitution reaction

C) Decomposition reaction

D) Neutralization reaction

12 / 23

In cracking, a large alkane produces:

A) Mixture of smaller alkanes and alkenes

B) Only carbon and hydrogen atoms separately

C) Only alkenes

D) Only alkanes

13 / 23

Which hydrocarbon will NOT undergo hydrogenation?

A) Ethyne

B) Ethane

C) Ethene

D) Propene

14 / 23

Which reagent is commonly used in hydrogenation reactions?

A) H₂

B) Cl₂

C) O₂

D) NH₃

15 / 23

Reduction of alkyl halides involves:

A) Removal of halogen atom

B) Addition of water

C) Formation of double bonds

D) Addition of oxygen

16 / 23

Which is correct for hydrogenation of propene?

A) C₃H₆ → C₃H₆+H₂

B) C₃H₆+H₂ → C₃H₆

C) C₃H₆+Cl₂ → C₃H₆Cl₂

D) C₃H₆+O₂ → CO₂

17 / 23

Cracking usually requires:

A) Low temperature and light

B) Electric current

C) Only water

D) High temperature and catalyst

18 / 23

Which is the correct general representation of hydrogenation?

A) Alkane → Alkene + H₂

B) Alkane + O₂ → CO₂+H₂O

C) Alkene → Alkane + O₂

D) Alkene + H₂ → Alkane

19 / 23

Why is nickel used in hydrogenation?

A) It reacts permanently with alkene.

B) It acts as fuel.

C) It lowers activation energy.

D) It produces hydrogen.

20 / 23

Which product is formed when bromoethane is reduced?

A) Ethyne

B) Ethane

C) Ethene

D) Ethanol

21 / 23

Which statement is correct about cracking?

A) It only produces alkanes.

B) It removes hydrogen atoms completely.

C) It increases molecular size.

D) It converts heavy hydrocarbons into useful smaller ones.

22 / 23

Which of the following is NOT a product of cracking?

A) Propene

B) Ethene

C) Butane

D) Oxygen gas

23 / 23

In alkane formation from alkyl halide, hydrogen replaces:

A) Oxygen atom

B) Carbon atom

C) Halogen atom

D) Hydrogen atom

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