Explanation

(b)
If acid is weak, its conjugate base (nucleophile) is strong and $vice\ versa.$
O O
$\ \ \ \ \ \ \ \ \ \ \ \ \ \parallel \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \parallel$
(A)$CH_{3} - C - O^{-}$ is conjugated base of $CH_{3}COH$ (I)
(B) $CH_{3}O^{-}$ is a conjugate base of $CH_{3}OH\ (II)$
(C) $CN^{-}$ is a conjugate base of HCN (III)
(D)$H_{3}$ [image:12_image303.emf] $SO_{3}^{-}$ is a conjugate base
Of [image:12_image304.emf]
Acidic nature of IV>I>III>II
and nucleophilicity of B>C>A>D.