Following reactions occur at cathode during the electrolysis of aqueous silver chloride solution:
Ag+(aq) + e⁻ → Ag(s) E° = +0.80 V
H+(aq) + e⁻ → ½H₂(g) E° = 0.00 V
On the basis of their standard reduction electrode potential (E°) values, which reaction is feasible at the cathode and why?

The relationship between the standard free energy change and emf of a cell reaction is given by:
ΔG° = -nFE°
Thus, more positive the standard reduction potential of a reaction, the more negative is the standard free energy change associated with the process and, consequently, the higher is the feasibility of the reaction.
Since, E°Ag+/Ag has a greater positive value than E°H+/H, the reaction which is feasible at the cathode is given by
Ag+(aq) + e⁻ → Ag(s)