Question

In which cell does the following reaction take place? \[2H_2(g) + O_2(g) \rightarrow 2H_2O(l)\]

• A. Lead accumulator battery
• B. Fuel cell
• C. Dry cell
• D. None of these

Hint:

A cell fed continuously with \(H_2\) and \(O_2\) gases producing only water is a fuel cell.

Answer 1

The Correct Option is B

Step 1: Identify the reaction. The overall change is hydrogen combining with oxygen to give water, releasing energy. A galvanic cell that runs on continuously supplied fuel gases is a fuel cell.
Step 2: The hydrogen-oxygen fuel cell. \(H_2\) and \(O_2\) are fed to porous electrodes in KOH.
Anode: \(H_2 + 2OH^- \rightarrow 2H_2O + 2e^-\)
Cathode: \(O_2 + 2H_2O + 4e^- \rightarrow 4OH^-\)
Overall: \(2H_2 + O_2 \rightarrow 2H_2O\).
Step 3: Rule out others. Lead accumulator uses \(Pb/PbO_2\) in \(H_2SO_4\); the dry cell uses \(Zn/MnO_2\). Neither has this hydrogen-oxygen reaction.
Step 4: Hence the reaction occurs in a fuel cell.
\[\boxed{\text{Fuel cell (option ii)}}\]