Consider the following bromides :
The correct order of $\mathrm{S}_{\mathrm{N}} 1$ reactivity is

• Correct answer
  A

  $B>C>A$
• B

  $B>A>C$
• C

  $C>B>A$
• D

  $A>B>C$

Solution

$\mathrm{S}_{\mathrm{N}} 1$ proceeds via carbocation intermediate, the most stable one forming the product faster. Hence reactivity order for $\mathrm{A}, \mathrm{B}, \mathrm{C}$ depends on stability of carbocation created.

Hence, the correct answer is option: 'A'.