MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

Unimolecular nucleophilic substitution (S_ N 1) reactions proceed via the formation of a carbocation intermediate in the rate-determining step. Polar protic solvents have high dielectric constants and are capable of hydrogen bonding. They stabilize both the carbocation intermediate and the leaving group anion through solvation. This stabilization lowers the activation energy required for the cleavage of the carbon-halogen bond, thereby increasing the rate of the S_ N 1 reaction. The strength of the nucleophile does not affect the rate of an S_ N 1 reaction because the nucleophile is not involved in the rate-determining step. Aprotic solvents generally favor S_ N 2 reactions. Answer: Polar protic solvent