Assertion (A): The rate of solvolysis of $(CH X_{3}) X_{3} C - Cl$ is much larger in 50% aqueous ethanol than in absolute ethanol. Reason (R): The transition state of the rate-determining step has considerable charge separation, which is stabilised better by the more polar, more strongly ionising solvent.

ABoth A and R are true, and R is the correct explanation of A
BBoth A and R are true, but R is not the correct explanation of A
CA is true but R is false
DA is false but R is true

Answer: A

Both statements are true. The slow step is ionisation, whose transition state resembles an ion pair. Water has the higher dielectric constant and hydrogen-bond donor ability, stabilising the developing

R X^{+}

and

Cl X^{-}

and lowering the activation energy, so R explains A.

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Answer: A

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