The increasing order of the rate of HCN addition to compound A-D is
(A) HCHO
(B) `CH_(3)COOH_(3)`
( C) `PhCOCH_(3)`
(D) `PhCOPh`

Options

A. `A lt B lt C lt D`
B. `D lt B lt C lt A`
C. `D lt C lt B lt A`
D. `C lt D lt B lt A`

Answer

C

Explanation

It is a nucleophilic addition whose reactivity depends upon the electrophilic character of carbonyl carbon and steric hindrance only. So, the ease of the reaction would be `HCHO gt CH_(3)COCH_(3) gt PhCOCH_(3) gt PhCOPh`.