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Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R) : Assertion (A) : SN2 reaction of C6H5CH2Br occurs more readily than the SN2 reaction of CH3CH2Br. Reason (R) : The partially bonded unhybridized p-orbital that develops in the trigonal bipyramidal transition state is stabilized by conjugation with the phenyl ring. In the light of the above statements, choose the most appropriate answer from the options given below :

1. (A) is not correct but (R) is correct
2. Both (A) and (R) are correct but (R) is not the correct explanation of (A)
3. Both (A) and (R) are correct and (R) is the correct explanation of (A)
4. (A) is correct but (R) is not correct

Correct answer: Both (A) and (R) are correct and (R) is the correct explanation of (A)

Solution

The assertion is correct because the presence of the phenyl ring in C6H5CH2Br stabilizes the transition state of the SN2 reaction through resonance, making the reaction proceed more readily compared to CH3CH2Br. The reason is also correct as it explains that the unhybridized p-orbital in the transition state is stabilized by conjugation with the phenyl ring, thus providing a valid rationale for the assertion.

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