AIIMS 2019 Chemistry Acidity of Organic Compounds MCQ Question
Assertion : The -chlorobenzoic acid is stronger than benzoic acid.
Reason : This is due to +M effect of chlorine.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Correct Answer
Detailed Explanation
The "-I" (inductive) effect of chlorine refers to its ability to withdraw electrons from the phenyl ring due to its high electronegativity, which stabilizes the negative charge on the carboxylate ion (−COO⁻) formed upon deprotonation of p-chlorobenzoic acid. This increased stability enhances the acidity of the acid compared to unsubstituted benzoic acid. Option A is misleading because, while chlorine is electronegative, it does not directly explain the increased acidity; option B is incorrect as chlorine does not donate electrons; and option D is irrelevant in this context, as the leaving group ability does not influence the acidity of the acid itself.
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