JEE Advanced · 2013 · 02 Jun 2013 · Paper 2 · Practical and Analytical Chemistry

An aqueous solution of a mixture of two inorganic salts, when treated with dilute $HCl$, gave a precipitate $(\mathbf{P})$ and a filtrate $(\mathbf{Q})$. The precipitate $\mathbf{P}$ was found to dissolve in hot water. The filtrate $(\mathbf{Q})$ remained unchanged, when treated with $H_{2}S$ in a dilute mineral acid medium. However, it gave a precipitate $(\mathbf{R})$ with $H_{2}S$ in an ammoniacal medium. The precipitate $\mathbf{R}$ gave a coloured solution $(\mathbf{S})$, when treated with ${\mathrm{H}}_2{\mathrm{O}}_2$ in an aqueous $NaOH$ medium.

The coloured solution $\mathbf{S}$ contains