Which of the following undergoes nucleophilic substitution exclusively by S _ N 1 mechanism?

Step-by-step solution

Aliphatic S_ N 1 reaction is carried out in two steps. In form of slow step Step (i) carbonium (carbocation) ion is formed and its formation is based upon the stability Stability order of carbocation C ₆ H ₅ + C H ₂ CH ₃- + C H - CH ₃ CH ₃- + C H ₂ and in step (ii) nucleophile is attracted towards the carbonium ion in form of fast step to give final product. Hence, in benzyl chloride, ethyl chloride and isopropyl chloride order of S _ N 1 reaction is benzyl chloride isopropyl chloride ethyl chloride In chlorobenzen