Question

A colorless aqueous solution contains nitrates of two metals, $X$ and $Y$. When it was added to an aqueous solution of $NaCl$, a white precipitate was formed. This precipitate was found to be partly soluble in hot water to give a residue $P$ and a solution $Q$. The residue $P$ was soluble in aq. $N{H}_3$ and also in excess sodium thiosulfate. The hot solution $Q$ gave a yellow precipitate with $KI$. The metals $X$ and $Y$, respectively, are

• A. $Ag$ and $Pb$
• B. $Ag$ and $Cd$
• C. $Cd$ and $Pb$
• D. $Cd$ and $Zn$

Answer 1

Answer: (A)

$X=Ag,Y=Pb$

$\underset{(P)}{\mathrm{AgCl}}+qa(N{H}_3)\to \underset{\text{Soluble}}{[Ag(N{H}_3{)}_2{]}^{+}}$ $\underset{(Q)\text{hot}}{PbC{l}_2}6KI\to \underset{\text{Yellow ppt }}{Pb{I}_2}$