Question

The second dissociation constant of fumaric acid is greater than maleic acid. Higher the dissociation constant of acid, more is the acidic character.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (B)

If both assertion and reason are true but reason is not the correct explanation of assertion

Answer 2

Both fumaric and maleic acids have two ionisable H ions i.e., protons. The maleate monoanion shows intramolecular H-bonding, whereas fumarate monoanion shows intermolecular H-bonding. Thus, fumarate monoanion requires more energy to give fumarate dianion. Hence, second dissociation of fumaric acid is more than that of maleic acid .