See image — Haloalkanes and Haloarenes Chemistry Question

💡 Solution & Explanation

Concept: The SN2 reaction follows a bimolecular mechanism, meaning both the substrate and the nucleophile are involved in the rate-determining step simultaneously. The rate law for an SN2 reaction is: Rate = k[substrate][nucleophile], making it second-order overall and first-order with respect to the nucleophile. Reasoning: Since the rate is first-order in nucleophile concentration, if the concentration of the nucleophile is increased by a factor of 10, the rate changes by 10^1 = 10. Mathematically: Rate_new = k[substrate][10 × nucleophile] = 10 × k[substrate][nucleophile] = 10 × Rate_old. Why other options fail: - Option (b): A factor of 10^2 would apply if the reaction were second-order in nucleophile, which it is not in a standard SN2 mechanism. - Option (c): Decreasing the rate makes no physical sense when increasing a reactant concentration in a reaction that depends on it. - Option (d): Remaining the same would be true only if the reaction were zero-order in nucleophile, as in SN1 reactions where the nucleophile is not involved in the rate-determining step. Therefore, the correct answer is A.