Which is/are ambident nucleophile(a)               (b) NH2–OH                                        (c) NH–CH3          (d) CH3–NO2(e) SO3                 (f)

An ambident nucleophile is a nucleophile that can attack from two or more places because it has two or more atoms with lone pair of electrons.

(a) Not specified (b) NH2–OH: This is an ambident nucleophile because it can attack from either the nitrogen atom or the oxygen atom. (c) NH–CH3: This is not an ambident nucleophile because it can only attack from the nitrogen atom. (d) CH3–NO2: This is an ambident nucleophile because it can attack from either the carbon atom or the oxygen atom. (e) SO3: This is not an ambident nucleophile because it can only attack from the sulfur atom. (f) Not specified

So, the ambident nucleophiles among the given options are NH2–OH and CH3–NO2.