Which of the following is a reaction that relies on electrolysis? A. conversion of iron to iron oxide
B. conversion of aluminum to aluminum oxide
C. conversion of water to hydrogen gas and oxygen gas
D. conversion of nitrogen gas and oxygen gas to nitrogen monoxide

C - choice

Explanation:

In pure water at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas. The half reaction, balanced with acid, is: Reduction at cathode: 2 H+(aq) + 2e− → H2(g) ... Oxidation at anode: 2 H2O(l) → O2(g) + 4 H+(aq) + 4e.

you need to have a picture of the atom that way we can answer it