An aqueous solution of a substance gives a white precipitate on treatment with dil. HCl which dissolves on heating, When H2S is passed through the hot acidic solution, black precipitate is obtained. T

Question

An aqueous solution of a substance gives a white precipitate on treatment with dil. HCl which dissolves on heating, When H2S is passed through the hot acidic solution, black precipitate is obtained. The substance is:

Prashant Kotian · Accepted Answer

Correct answer: D. 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).

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