Identify the reagents shown in bold in the following equations as nucleophiles or electrophiles:

Electrophiles are electron-deficient species and can receive an electron pair. On the other hand, nucleophiles are electron-rich species and can donate their electrons.

Here, $\mathrm{HO}^{-}$acts as a nucleophile as it is an electron-rich species, i.e., it is a nucleus-seeking species.

Here, ${ }^{-} \mathrm{CN}$ acts as a nucleophile as it is an electron-rich species, i.e., it is a nucleus-seeking species.

Here, $\mathrm{CH}_{3} \stackrel{+}{\mathrm{C}} \mathrm{O}$ acts as an electrophile as it is an electron-deficient species.