Answer: -1.
- A 0
- B +1
- C -1
- D +7
Correct answer: C. -1
Explanation: In HCl, H is +1 and the molecule is neutral, so Cl must be -1.
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.