Fuel cell involves ______.

The correct answer is Option (1) → The reaction of \(H_2\) with \(O_2\) to give \(H_2O\)

A fuel cell is a galvanic cell that converts the energy of combustion of a fuel such as hydrogen, methane or methanol directly into electrical energy, with the reactants fed in continuously. In the hydrogen–oxygen fuel cell, the gases are bubbled through porous carbon electrodes into concentrated aqueous NaOH:

    \( \displaystyle \text{Anode: } \ce{2H2(g) + 4OH^-(aq) -> 4H2O(l) + 4e^-} \)

    \( \displaystyle \text{Cathode: } \ce{O2(g) + 2H2O(l) + 4e^- -> 4OH^-(aq)} \)

    \( \displaystyle \text{Cell reaction: } \ce{2H2(g) + O2(g) -> 2H2O(l)} \)

So the fuel cell involves the reaction of hydrogen with oxygen to give water. The water formed in the cells of the Apollo space programme was used as drinking water by the astronauts.

Why the other options are incorrect

• Option (2) The splitting of \(H_2O\) to give \(O_2\) — Incorrect. Splitting water needs electrical energy to be supplied; that is electrolysis, the reverse of what a fuel cell does.

• Option (3) The splitting of \(H_2O\) to give \(H_2\) — Incorrect. This is again electrolysis of water, which consumes electricity instead of producing it.

• Option (4) The reaction of \(H_2\) and \(H_2O\) to give \(O_2\) — Incorrect. Hydrogen is a reducing agent; it cannot take oxygen out of water to release \( \ce{O2} \), and no such cell reaction exists.

NCERT (2026-27 edition):
Fuel Cells – …