Read the following passage given below and answer the question.
Production of electricity by thermal plants is not very efficient method. It is now possible to make cells in which reactants are fed continuously to the electrodes and products are also removed continuously. One of the most successful fuel cells is hydrogen fuel cell.
In Hydrogen fuel cell, which gas is undergoing oxidation?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Only hydrogen
Oxidation is loss of electrons (rise in oxidation state); reduction is gain of electrons. In the fuel cell the two gases react at different electrodes:
\( \displaystyle \text{Anode: }\ce{2H2(g) + 4OH^-(aq) -> 4H2O(l) + 4e^-} \)
\( \displaystyle \text{Cathode: }\ce{O2(g) + 2H2O(l) + 4e^- -> 4OH^-(aq)} \)
\( \displaystyle \text{Cell reaction: }\ce{2H2(g) + O2(g) -> 2H2O(l)} \)
At the anode, hydrogen gives up electrons: its oxidation state rises from 0 in \( \ce{H2} \) to +1 in \( \ce{H2O} \), so hydrogen is oxidised. At the cathode, oxygen takes up these electrons and its oxidation state falls from 0 to −2 in \( \ce{OH-} \), so oxygen is reduced.
Option (2) Only oxygen — Incorrect. Oxygen gains electrons at the cathode, so it is reduced, not oxidised.
NCERT (2026-27 edition):
Fuel Cells – “… The electrode reactions are given below:
Cathode: O2(g) + 2H2O(l) + 4e– → 4OH–(aq)
Anode: 2H2(g) + 4OH–(aq) → 4H2O(l) + 4e–”