Question

The ion that cannot be precipitated by both $HCl$ and $H_{2}S$ is :

• A. $P{b}^{2+}$
• B. $C{u}^{+}$
• C. $A{g}^{+}$
• D. $S{n}^{2+}$

Answer 1

Answer: (D)

The explanation for correct option:

Option(B) $S{n}^{+2}$

• The ion that cannot be precipitated by both $HCl$ and $H_{2}S$ is $S{n}^{2+}$.

• $S{n}^{2+}$ cannot be precipitated by $HCl$, because it forms soluble stannous chloride.

$S{n}^{+2}+2HCl\left(aq\right)⟶SnC{l}_2\left(aq\right)+2H^{+}$

• but is precipitated by $H_{2}S$ as a chocolate-colored precipitate of SnS, soluble in yellow ammonium sulphide.

$S{n}^{+2}+H_{2}S\left(aq\right)⟶SnS\downarrow \left(s\right)+2H^{+}$

• while $P{b}^{+2},C{u}^{+2},A{g}^{+}$ can be precipitated by HCl as well as as their insoluble chlorides and sulfides respectively.