Increasing rate of S N 1 reaction in the following compounds is: (I) (II) (III) (IV)

Step-by-step solution

The rate of S N 1 reaction ∝ stability of carbocation stability of carbocation ∝ + v e charge delocation. ∝ + M ,   + H C ,   + I Order of effect effectiveness + M > + H C > + I   ( + M   ) >   ( - I ) D C A B So, order of stability B < A < C < D