Which of the following reactions is used to make a fuel cell?

Which of the following reactions is used to make a fuel cell?
  1. $\begin{aligned} & \mathrm{Cd}_{(s)}+2 \mathrm{Ni}(\mathrm{OH})_{3(s)} \\ & \rightarrow \mathrm{CdO}_{(s)}+2 \mathrm{Ni}(\mathrm{OH})_{2(s)}+\mathrm{H}_2 \mathrm{O}_{(l)}\end{aligned}$
  2. $\mathrm{Pb}_{(s)}+\mathrm{PbO}_{2(s)}+2 \mathrm{H}_2 \mathrm{SO}_{4(a q)}$ $\rightarrow 2 \mathrm{PbSO}_{4(s)}+2 \mathrm{H}_2 \mathrm{O}_{(l)}$
  3. $2 \mathrm{H}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \rightarrow 2 \mathrm{H}_2 \mathrm{O}(l)$
  4. $2 \mathrm{Fe}_{(s)}+\mathrm{O}_{2(g)}+4 \mathrm{H}^{+}{ }_{(a q)} \rightarrow 2 \mathrm{Fe}^{2+}{ }_{(a q)}+2 \mathrm{H}_2 \mathrm{O}_{(l)}$

Solution

Fuel cells are galvanic cells in which chemical energy of fuels is directly converted into electrical en ergy. e.g., Hydrogen - oxygen fuel cell.

Asked in: MHT CET Full Test 3

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