WAEC Chemistry 2025 Paper

Concept:Ionic compounds form through the transfer of electrons between a metal and a non-metal or between polyatomic ions, while non-metal oxides are usually covalent.Explanation:$\mathrm{AgCl}$ contains $\mathrm{Ag}^+$ and $\mathrm{Cl}^-$ ions, so it is ionic.$\mathrm{KNO}_3$ contains $\mathrm{K}^+$ and $\mathrm{NO}_3^-$ ions, so it is ionic.$\mathrm{NO}_2$ is formed by the sharing of electrons between nitrogen and oxygen atoms, making it covalent.$(\mathrm{NH}_4)_2\mathrm{CO}_3$ contains $\mathrm{NH}_4^+$ and $\mathrm{CO}_3^{2-}$ ions, so it is ionic.Therefore, the compound that is not ionic is $\mathrm{NO}_2$.Answer:$\mathrm{NO}_2$ (Option C).