Answer: 1 : 5.
- A 1 : 5
- B 1 : 3
- C 1 : 6
- D 1 : 2
Correct answer: A. 1 : 5
Explanation: MnO4− gains 5 electrons while each Fe2+ loses 1; balancing electrons needs 5 Fe2+ per MnO4−.
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.