2024 O Level Chem P1 Q25 — Simple Cell / Electrochemistry Solution

Answer: D. In a Zn|Cu simple cell, zinc is the more reactive metal. Zinc loses electrons and is oxidised at the zinc electrode: \(\text{Zn} \rightarrow \text{Zn}^{2+} + 2\text{e}^{-}\). The zinc rod is the negative electrode (anode); copper is the positive electrode (cathode).

A is wrong: in the electrolyte, anions migrate towards the anode (zinc), not away from it — i.e., from copper to zinc, opposite to the direction stated.

B is wrong: electrons flow externally from the anode (Zn) to the cathode (Cu), not Cu to Zn.

C is wrong: copper is the cathode where reduction occurs (\(\text{Cu}^{2+} + 2\text{e}^{-} \rightarrow \text{Cu}\)), not oxidation.