Answer: H 2 O 2.
- A KMnO<sub>4</sub>
- B F<sub>2</sub>
- C H<sub>2</sub>O<sub>2</sub>
- D K<sub>2</sub>Cr<sub>2</sub>O<sub>7</sub>
Correct answer: C. H<sub>2</sub>O<sub>2</sub>
Explanation: H₂O₂ can oxidise (reducing to H₂O, O changes from -1 to -2) or reduce (oxidising to O₂, O changes from -1 to 0), acting as both an oxidising and a reducing agent depending on the conditions.
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.