Answer: CuSO4 + SO2 + H2O.
- A CuSO4 + H2
- B CuSO4 + SO2 + H2O
- C Cu2SO4 + H2
- D CuO + H2S
Correct answer: B. CuSO4 + SO2 + H2O
Explanation: Concentrated H₂SO₄ is an oxidising acid: Cu + 2H₂SO₄(conc.) → CuSO₄ + SO₂↑ + 2H₂O. Dilute H₂SO₄ cannot oxidise copper as Cu is below H in the electrochemical series.
Electron transfer in a redox reaction: zinc loses electrons (oxidised, acts as reducing agent) and copper(II) ions gain those same electrons (reduced, acts as oxidising agent).
Concept context
Master electron transfer in chemistry: assign oxidation states, balance half-reactions, identify oxidising and reducing agents, and connect redox to everyday reactions.