JEE Main · 2023 · 08 Apr 2023 · Shift 1 · Redox Reactions and Electrochemistry

The spontaneous cell reaction is split into oxidation at the anode and reduction at the cathode. Hydrogen is oxidised, $\frac{1}{2}{\mathrm{H}}_2\to {\mathrm{H}}^{+}+e^{-}$, so the platinum hydrogen electrode is the anode and its solution must supply and accommodate ${\mathrm{H}}^{+}$. At the cathode silver chloride is reduced, $\mathrm{AgCl}+e^{-}\to \mathrm{Ag}+\mathrm{C}{\mathrm{l}}^{-}$, so solid $\mathrm{AgCl}$ in contact with silver is required and the liberated $\mathrm{C}{\mathrm{l}}^{-}$ must enter the same solution. A single $\mathrm{HCl}$ solution provides both the ${\mathrm{H}}^{+}$ of the anode process and the $\mathrm{C}{\mathrm{l}}^{-}$ of the cathode process, so the cell is $\mathrm{Pt}|{\mathrm{H}}_2(\mathrm{g})|\mathrm{HCl}(\mathrm{soln})|\mathrm{AgCl}(\mathrm{s})|\mathrm{Ag}$.