Answer: Reducing agent.
- A Oxidising agent
- B Reducing agent
- C Acid
- D Electrolyte
Correct answer: B. Reducing agent
Explanation: The reducing agent is the substance that loses electrons (is oxidised) and thereby reduces another substance.
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.