WAEC Chemistry 2020 Paper

Concept:A dative bond, also called a coordinate covalent bond, forms when one atom supplies both electrons of the shared pair.Explanation:In $\mathrm{NH}_4^+$, the nitrogen atom in $\mathrm{NH}_3$ carries a lone pair of electrons.The hydrogen ion, $\mathrm{H}^+$, has no electrons of its own.Nitrogen donates its lone pair to $\mathrm{H}^+$ to form the bond.Thus, the bond between $\mathrm{NH}_3$ and $\mathrm{H}^+$ in $\mathrm{NH}_4^+$ is a dative bond.Answer:A. dative