Answer: +6.
- A +4
- B +6
- C -2
- D +2
Correct answer: B. +6
Explanation: In H₂SO₄: 2(+1) + S + 4(-2) = 0. S = 8 - 2 = +6.
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.