Answer: The same element is simultaneously oxidised and reduced.
- A Two largely different elements undergo a simultaneous oxidation-reduction exchange
- B The same element is simultaneously oxidised and reduced
- C Mainly a single reduction half-reaction occurs without any oxidation
- D Mainly a single oxidation half-reaction occurs without any reduction
Correct answer: B. The same element is simultaneously oxidised and reduced
Explanation: In a disproportionation reaction, a single substance acts as both oxidising and reducing agent; the same element changes to two different oxidation states.
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.