An aqueous solution of a substance gives a white precipitate on treatment with dil. HCl which dissol — Qualitative and Quantitative Analysis Chemistry Question

💡 Solution & Explanation

Step 1: Adding dilute HCl to a Group I cation (such as Pb2+, Ag+, Hg22+) precipitates it as a white chloride. Step 2: Lead(II) chloride (PbCl2) is uniquely soluble in hot water, so the precipitate dissolves completely upon heating the mixture. Step 3: When H2S gas is passed through this hot solution containing Pb2+ ions, it reacts to precipitate highly insoluble black lead(II) sulfide (PbS). This identifies the metal ion as Pb2+, corresponding to option (d).