In the reaction ${2H}_2(\mathrm{g})+{\mathrm{O}}_2(\mathrm{g})\to {2H}_2\mathrm{O}(\mathrm{l})$, which of the following species is undergoing oxidation?

Step-by-step solution

1. Identify oxidation states: H in H2 is 0; in H2O it is +1. O in O2 is 0; in H2O it is -2.
2. Since H goes from 0 to +1 (loss of electrons) it is oxidised.
3. Therefore hydrogen gas (H2) is the species undergoing oxidation.
4. Oxygen is reduced and H2O is the product of reduction.
5. Thus the correct choice is H2.

Concept tested: Oxidation vs reduction identification

Published 13 October 2026 · How this solution was prepared and checked