WAEC Chemistry 2025 Paper

Concept:Covalent compounds are formed between nonmetals, while ionic compounds usually contain a metal combined with a nonmetal or polyatomic ion.Explanation:$\mathrm{NO}_2$, $\mathrm{SO}_3$, and $\mathrm{SO}_2$ are all made up of nonmetal elements only, so they are covalent compounds.$\mathrm{KNO}_3$ contains potassium ($\mathrm{K}$), which is a metal, along with the nitrate polyatomic ion ($\mathrm{NO}_3^-$).The bond between the metal and the nitrate ion is ionic.Thus, $\mathrm{KNO}_3$ is not covalent.Answer:D. $\mathrm{KNO}_3$