In the following pairs of halogen compounds, which compound undergoes faster S_N1 reaction?

(i)

(ii)

Reason: SN₁ occurs in two steps. In the first step, carbocation forms. The rate of reaction in S_N1 depends upon the stability of the carbocation, greater the stability faster the reaction. Tertiary (3°) carbocation is more stable than secondary (2°), which is further stable than primary (1°)

By using this

i) Tert-Butyl Chloride (3°) reacts faster than 3-Chloropentane (2°)

ii) 2-Chloro heptane (2°) is more reactive than 1-Chloro hexane (1°)