Standard electrode potential of cell ${\mathrm{H}}_2\left|{\mathrm{H}}^{+}\right|\left|{\mathrm{Ag}}^{+}\right|\mathrm{Ag}$ is (SRP of Ag electrode = 0.8 V)

$\frac{1}{2}{\mathrm{H}}_2\left|{\mathrm{H}}^{+}\right|\left|{\mathrm{Ag}}^{+}\right|\mathrm{Ag}$

${\mathrm{E}}_{\text{cell}}^{\mathrm{o}}={\mathrm{E}}_{\text{cathode}}^{\mathrm{o}}-{\mathrm{E}}_{\text{Anode}}^{\mathrm{o}}={\mathrm{E}}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^0-{\mathrm{E}}_{{\mathrm{H}}^{+}/\frac{1}{2}{\mathrm{H}}_2}^0$

$=\left(0.80\right)-\left(0.0\right)=0.80V$