Answer: Reducing agent (H 2 O 2 is oxidised: O from -1 to 0 in O 2 ).
- A Oxidising agent (Mn<sup>7+</sup> → Mn<sup>2+</sup>, so KMnO<sub>4</sub> is reduced by H<sub>2</sub>O<sub>2</sub>)
- B Reducing agent (H<sub>2</sub>O<sub>2</sub> is oxidised: O from -1 to 0 in O<sub>2</sub>)
- C Catalyst
- D Neither oxidised nor reduced
Correct answer: B. Reducing agent (H<sub>2</sub>O<sub>2</sub> is oxidised: O from -1 to 0 in O<sub>2</sub>)
Explanation: In this reaction, H₂O₂ is the reducing agent: O in H₂O₂ goes from -1 to 0 in O₂ (loses electrons, oxidised). KMnO₄ is the oxidising agent: Mn goes from +7 to +2 (gains electrons, reduced).
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.