MHT CET Chemistry Question (2026) — Solution

Step-by-step solution

The rate of an SN ^1 reaction depends on the stability of the carbocation formed and the leaving group ability of the halide ion. Since the alkyl group is the same in all the given options, the carbocation formed is the tert-butyl carbocation, ( CH _3)_3 C ^+, in each case. The rate of reaction will therefore depend on the leaving group ability of the halide ion. A better leaving group leads to a faster reaction. The leaving group ability increases as the size of the halogen atom increases and the carbon-halogen bond strength decreases. The order of bond dissociation energy is C-F > C-Cl > C-Br > C-I . Thus, the iodide ion ( I ^-) is the best leaving group among the halides. Therefore, ( CH _3)_3 C-I undergoes the SN ^1 reaction most readily. Answer: ( CH _3)_3 C-I