Chemistry 9th Chap 14 : Topic 3 - Maryam Publications

Chemistry Chapter 14 : Topic 3

Substitution Reactions

1 / 18

In a chemical reaction, methane reacts with chlorine in sunlight to form chloromethane and hydrogen chloride. This reaction occurs in such a way that one hydrogen atom in methane is replaced by a chlorine atom. Which type of reaction is this?

A) Addition reaction

B) Neutralization reaction

C) Decomposition reaction

D) Substitution reaction

2 / 18

A student observes that when ethane reacts with bromine in the presence of UV light, one hydrogen atom is replaced by a bromine atom. Which statement best explains this process?

A) New atoms are added without removing any existing atom.

B) The compound breaks into simpler substances.

C) Two compounds exchange ions in solution.

D) One atom in the molecule is replaced by another atom.

3 / 18

During a laboratory experiment, a hydrocarbon reacts with chlorine gas under sunlight, producing a chloro-derivative and hydrochloric acid. The key feature of this reaction is:

A) Replacement of hydrogen atom by chlorine atom

B) Exchange of electrons without bond breaking

C) Formation of a larger molecule by joining atoms

D) Breaking of molecule into carbon and hydrogen

4 / 18

In substitution reactions of alkanes, which of the following best describes the change that occurs?

A) Carbon chain length increases.

B) Double bond is formed between carbon atoms.

C) Entire molecule is broken into elements.

D) One atom or group in the molecule is replaced.

5 / 18

Methane undergoes a reaction with chlorine in presence of sunlight forming CH₃Cl. What happens to methane during this process?

A) Carbon atom is replaced by chlorine.

B) One hydrogen atom is replaced by chlorine.

C) Methane decomposes into carbon and hydrogen.

D) All hydrogen atoms are removed.

6 / 18

Which statement correctly defines a substitution reaction in organic chemistry?

A) Two molecules combine to form a single product.

B) One atom or group is replaced by another atom or group.

C) Ions exchange between compounds in solution.

D) A compound splits into simpler substances.

7 / 18

When ethane reacts with chlorine under UV light, one hydrogen atom is replaced by chlorine. Which product is formed?

A) Ethanol

B) Ethene

C) Ethanoic acid

D) Chloroethane

8 / 18

Which of the following is the most important characteristic of substitution reactions?

A) Only occurs in aqueous solutions

B) Replacement of atoms or groups within a molecule

C) Formation of only ionic compounds

D) No change in atoms of reactants

9 / 18

A hydrocarbon reacts with chlorine in sunlight, and hydrogen chloride is produced as a by-product. This strongly indicates that:

A) Addition reaction has occurred

B) Substitution reaction has occurred

C) Neutralization reaction has occurred

D) Precipitation reaction has occurred

10 / 18

Which of the following best represents a substitution reaction at the molecular level?

A) A+B → AB

B) AB → A+B

C) A+B → C+D (exchange only ions)

D) A-B+C → A-C+B

11 / 18

In substitution reactions of saturated hydrocarbons, what is generally replaced?

A) Hydrogen atoms bonded to carbon

B) Double bonds between carbons

C) Carbon atoms in chain

D) Entire functional group

12 / 18

A reaction is observed where bromine replaces hydrogen in an alkane molecule. Which term best describes this reaction?

A) Combustion reaction

B) Combination reaction

C) Substitution reaction

D) Redox precipitation

13 / 18

Why is methane considered to undergo substitution rather than addition when reacting with chlorine?

A) Because one hydrogen atom is replaced, not added.

B) Because methane has a double bond.

C) Because oxygen is always involved.

D) Because carbon atoms are removed.

14 / 18

Which statement is NOT correct about substitution reactions?

A) It often occurs in organic compounds.

B) Atoms or groups are replaced.

C) New products are formed.

D) Entire molecule is always destroyed.

15 / 18

In the reaction of ethane with chlorine, UV light is required. This condition mainly helps in:

A) Increasing molecular size

B) Forming ionic bonds

C) Preventing reaction from occurring

D) Breaking bonds to allow substitution

16 / 18

Which of the following best explains the term “substitution”?

A) Mixing two substances without reaction

B) One atom replacing another in a compound

C) Splitting of compound into ions

D) Formation of precipitate in solution

17 / 18

In substitution reactions of alkanes, what is the role of halogens like chlorine or bromine?

A) They replace hydrogen atoms in hydrocarbons.

B) They break carbon chains completely.

C) They form only ionic compounds.

D) They act as catalysts only.

18 / 18

A student concludes that a reaction is substitution if:

A) Heat is always released.

B) New bonds are formed without breaking old ones.

C) One atom or group in a molecule is replaced by another.

D) Only gases are produced.

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