Chemistry - Salt Analysis Question with Solution | TestHub

Compound A is a mixture of SO₃²⁻ (aq) and S₂O₃²⁻ (aq). When A reacts with Zn + NaOH, the sulfite (SO₃²⁻) and thiosulfate (S₂O₃²⁻) are reduced to release H₂S gas (B). The gas B (H₂S) then reacts with acidified dichromate (Cr₂O₇²⁻/H⁺) to produce elemental sulfur, which appears as a white turbidity (C). When A is heated directly ($\Delta$), it undergoes disproportionation or decomposition; specifically, for thiosulfate (S₂O₃²⁻), heating in an acidic or specific medium can lead to the formation of SO₂ and S, where D represents the identified species SO₂ or the product pair. Therefore, species A and D are respectively SO₃²⁻ (aq), S₂O₃²⁻ (aq) and SO₂, making the correct option (C).