Answer: 0.
- A +1
- B -1
- C 0
- D Depends on the element
Correct answer: C. 0
Explanation: Any element in its free (uncombined) state has an oxidation state of zero, regardless of the element.
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.