Answer: +6.
- A +7
- B +4
- C +2
- D +6
Correct answer: D. +6
Explanation: Mn + 4(−2) = −2, so Mn = +6 in the manganate ion (compared with +7 in permanganate).
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.