JAMB Chemistry 2018 Paper

Concept: Sulphides of copper and other group II metals resist dissolving in dilute acids.Explanation: Dilute hydrochloric acid readily dissolves sulphides like $\mathrm{FeS}$, $\mathrm{ZnS}$, and $\mathrm{Na_2S}$.However, $\mathrm{CuS}$ is highly insoluble in dilute acids.It remains as a black precipitate when dilute $\mathrm{HCl}$ is added.So among the given options, copper(II) sulphide is the one that does not dissolve in dilute hydrochloric acid.Answer: Option B. $\mathrm{CuS}$