Chemistry 9th Chap 13 : Topic 5 - Maryam Publications

Chemistry Chapter 13 : Topic 5

Structural Isomerism

1 / 18

Structural isomers are an important concept in organic chemistry. Which of the following best defines structural isomers?

A) Compounds having identical molecular and structural formula.

B) Compounds having same molecular formula but different arrangement of atoms (structural formula).

C) Compounds having different molecular formula but same structural formula.

D) Compounds having same physical properties but different chemical formula.

2 / 18

Butane (C₄H₁₀) exists in two structural isomeric forms. Which statement correctly explains this phenomenon?

A) Hydrogen atoms change their atomic number in different structures.

B) Same atoms are arranged in different structural patterns forming different compounds.

C) Carbon atoms form ionic bonds in different ways.

D) The molecular formula changes depending on temperature.

3 / 18

Which pair correctly represents structural isomers of C₄H₁₀?

A) CH₃ CH₂ CH₂ CH₃ and CH₃ CH (CH₃) CH₃

B) C₂H₄ and C₄H₈

C) CH₃OH and C₂H₅OH

D) CH₄ and C₂H

4 / 18

Which statement best explains why structural isomers have different physical properties?

A) Their atoms are arranged differently, affecting intermolecular forces.

B) They have different molecular formulas.

C) They have different atomic numbers.

D) They contain different elements.

5 / 18

The compound CH₃ CH₂ CH₂ CH₃ and CH₃CH(CH₃)CH₃ are examples of:

A) Structural isomers

B) Optical isomers

C) Geometrical isomers

D) Functional isomers

6 / 18

Which of the following correctly represents isobutane?

A) CH₃ CH₂ CH₃

B) CH₃ CH₂ CH₂ CH₃

C) CH₂ CH₂ CH₂ CH₂

D) CH₃ CH (CH₃) CH₃

7 / 18

But-1-ene and but-2-ene are structural isomers of:

A) C₂H₄

B) C₃H₆

C) C₄H₁₀

D) C₄H₈

8 / 18

Which of the following pairs shows position isomerism?

A) CH₃ CH₂ CH₂ CH₃ and CH₃ CH (CH₃) CH₃

B) CH₄ and C₂H₆

C) O₂ and O₃

D) But-1-ene and But-2-ene

9 / 18

How many structural isomers are possible for C₄H₁₀ according to the syllabus?

A) 2

B) 1

C) 4

D) 3

10 / 18

Which statement is true about structural isomers of C₄H₈ given in syllabus?

A) They contain different numbers of hydrogen atoms.

B) They are identical compounds.

C) They have different molecular formulas.

D) They include but-1-ene and but-2-ene.

11 / 18

The compound CH₃ CH₂ CH₂ CH₃ and its isomer CH₃ CH (CH₃) CH₃ differ mainly in:

A) Carbon chain arrangement

B) Molecular formula

C) Number of hydrogen atoms

D) Type of elements present

12 / 18

Structural isomerism is best described as:

A) Same physical state but different elements

B) Same structure, different formula

C) Same formula, different arrangement of atoms

D) Different elements combined together

13 / 18

Which statement correctly compares but-1-ene and but-2-ene?

A) They differ in number of carbon atoms.

B) They differ in functional group.

C) They differ in molecular formula.

D) They differ in position of double bond.

14 / 18

Which of the following is NOT a structural isomer of C₄H₁₀?

A) CH₃ CH (CH₃) CH₃

B) Both A and B

C) CH₃ CH₂ CH₂ CH₃

D) CH₃ CH₂ CH₃

15 / 18

Why do structural isomers of the same compound show different boiling points?

A) They contain different elements.

B) They have different molecular formulas.

C) They have different atomic numbers.

D) Their shapes affect intermolecular attraction.

16 / 18

Which of the following correctly describes chain isomerism in C₄H₁₀?

A) Same structure, different isotopes

B) Same molecular formula, different carbon skeleton arrangement

C) Same chain, different functional group

D) Different molecular formula, same structure

17 / 18

The structural formula CH₃ CH (CH₃) CH₃ represents:

A) n-butane

B) but-1-ene

C) but-2-ene

D) isobutene

18 / 18

Which feature is common in all structural isomers?

A) Same boiling point

B) Same structural formula

C) Same molecular formula

D) Same chemical properties always

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