When a KI solution is added to a metal nitrate, a black precipitate is produced which dissolves in an excess of KI to give an orange solution. The metal ion is:

Question

Prashant Kotian · Accepted Answer

Correct answer: B. Step 1: The reaction of bismuth(III) ions with iodide ions (I-) initially forms a dark brown/black precipitate of bismuth(III) iodide (BiI3). Step 2: The black BiI3 precipitate reacts with excess iodide ions to form a highly stable, soluble tetraiodobismuthate(III) complex anion: BiI3 + I- -> [BiI4]-. Step 3: The [BiI4]- complex solution exhibits a characteristic orange/yellow-orange color. This confirms the presence of Bi3+, matching option (b).

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