Assertion (A): Alkyl iodide (R–I) undergoes S_N2 reaction faster than alkyl chloride (R–Cl). Reason (R): Iodine is a better leaving group because of its large size.

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NEET Chemistry QUESTION #1074

Question 1

Assertion (A): Alkyl iodide (R–I) undergoes S\(_N\)2 reaction faster than alkyl chloride (R–Cl). Reason (R): Iodine is a better leaving group because of its large size.

A is true but R is false
A is false but R is true
Both A and R are true and R is the correct explanation of A✔️
Both A and R are true but R is not the correct explanation of A

Correct Answer Explanation

Both A and R are true. R–I reacts faster in S\(_N\)2 than R–Cl because I\(^-\) is a much better leaving group — it is larger, more polarizable, and the C–I bond is weaker. The large size of iodine means the C–I bond is longer and weaker, making it easier to break. R correctly explains A.

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