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.
(a) `CH_(3)COOH+HO^(-)toCH_(3)COO^(-)+H_(2)O`
Here, `HO^(–)` acts as a nucleophile as it is an electron-rich species, i.e., it is a nucleus- seeking species.
(b) `CH_(3)COCH_(3)+overset(-)CNto(CH_(3))_(2)C(CN)(OH)`
Here, `""^(–)CN` acts as a nucleophile as it is an electron-rich species, i.e., it is a nucleus- seeking species.
(c ) `C_(6)H_(6)+CH_(3)overset(+)COtoC_(6)H_(5)COCH_(3)`
Here, `CH_(3)overset(+)CO` acts as an electrophile as it is an electron-deficient species.