Assertion (A): Inversion of configuration is observed in the S$_\mathrm{N}$2 reaction. Reason (R): The reaction proceeds with the formation of a carbocation.

(C) Assertion (A) is true, but Reason (R) is false.

(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).

(D) Assertion (A) is false, but Reason (R) is true.

CBSE Class 12 · 2024 · Haloalkanes and HaloarenesMultiple Choice

Assertion (A): Inversion of configuration is observed in the S

_{N}

2 reaction.
Reason (R): The reaction proceeds with the formation of a carbocation.

(A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
(B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(C)Assertion (A) is true, but Reason (R) is false.✓ Correct
(D)Assertion (A) is false, but Reason (R) is true.

Answer: (C)

Solution

_{N}

2 is a one-step, concerted backside attack — the configuration inverts (Walden inversion), so A is true.
No carbocation is involved in S

_{N}

2 (carbocations belong to S

_{N}

1), so R is false.
Correct option: (C).

CBSE Class 12 Board · 2024 · Single correct option

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