JEE Advanced 2013 · Paper 2, Chemistry question 34

Paragraph for Questions 33 and 34

An aqueous solution of a mixture of two inorganic salts, when treated with dilute HCl, gave a precipitate (P) and a filtrate (Q). The precipitate P was found to dissolve in hot water. The filtrate (Q) remained unchanged, when treated with $\ce{H2S}$ in a dilute mineral acid medium. However, it gave a precipitate (R) with $\ce{H2S}$ in an ammoniacal medium. The precipitate R gave a coloured solution (S), when treated with $\ce{H2O2}$ in an aqueous NaOH medium.