The number of nucleophiles in the following list is $CH_3NH_2$,$CH_3CHO$,$C_2H_4$,$CH_3SH$.

What is the decreasing order of basic strength for the following species: $\mathop O\limits^\Theta H, \mathop N\limits^\Theta H_2, HC \equiv \mathop C\limits^\Theta, CH_3 - \mathop C\limits^\Theta H_2$?

Which of the following is a nucleophile?

Identify the electrophilic centers in the following: $CH_3-CHO$,$CH_3-CN$,and $CH_3-I$.

What is the correct order of basicity?

Identify the reagents shown in bold in the following equations as nucleophiles or electrophiles:
$(a) \ CH_{3}COOH + \mathbf{HO^{-}} \to CH_{3}COO^{-} + H_{2}O$
$(b) \ CH_{3}COCH_{3} + \mathbf{CN^{-}} \to (CH_{3})_{2}C(CN)OH$
$(c) \ C_{6}H_{6} + \mathbf{CH_{3}C^{+}=O} \to C_{6}H_{5}COCH_{3} + H^{+}$