The correct acidity order of the following is

Options

A. III `gt` IV `gt` II `gt` I
B. IV `gt` III `gt` I `gt` II
C. III `gt` II `gt` I `gt` IV
D. II `gt` III `gt` IV `gt` I

Answer

A

Explanation

A carboxylic acid is stronger acid than phenol, hence both III and IV are stronger acids than both I and II. Also (IV) has a methyl group that possesses electron donating inductive effect and decreases the acid strength. Therefore (III) is stronger acid than (IV). Between (I) and (II), the dominant electron withdrawing inductive effect of chlorine increases acidic strength of phenol slightly, hence (II) is stronger acid than (I). Thus, the overall order is (a) III `gt` IV `gt` II `gt` I