JAMB Chemistry 2019 Paper

Concept:White precipitate with silver nitrate soluble in aqueous ammonia indicates chloride ions; white precipitate soluble on heating indicates lead ions.Explanation:$X + \mathrm{AgNO_3}$ gives a white precipitate soluble in $\mathrm{NH_3}$, so $X$ contains $\mathrm{Cl^-}$.$Y$ added to $X$ forms a white precipitate soluble when heated, so $Y$ contains $\mathrm{Pb^{2+}}$.$\mathrm{Pb^{2+} + 2Cl^- \to PbCl_2 \downarrow}$$\mathrm{PbCl_2}$ is soluble in hot water.Answer:$X$ contains $\mathrm{Cl^-}$, $Y$ contains $\mathrm{Pb^{2+}}$; the intended option is C. $\mathrm{Pb^{2+}, Cl^-}$.