For the cell $\mathrm{Zn}(\mathrm{s})\left|\mathrm{Zn}^{2+}(\mathrm{aq}) \| \mathrm{M}^{\mathrm{x}+}(\mathrm{aq})\right| \mathrm{M}(\mathrm{s})$, different half cells and their standard electrode potentials are given below:
If $\mathrm{E}_{\mathrm{Zn}^{2+} / \mathrm{Zn}}^{\mathrm{O}}=-0.76 \mathrm{~V}$, which cathode will give a maximum value of $E_{\text {cell }}^{\circ}$ per electron transferred?
Correct Option: 1
$\mathrm{Zn}+2 \mathrm{Ag}^{+} \longrightarrow 2 \mathrm{Ag}+\mathrm{Zn}^{2+} \quad\left(n=2 e^{-}\right)$
$\mathrm{E}_{\text {cell }}^{\circ}=\left(\mathrm{E}_{\text {R.P. }}^{\circ}\right)_{\text {cathode }}-\left(\mathrm{E}_{\text {R.P. }}^{\circ}\right)_{\text {anode }}$
$=0.80-(-0.76)=1.56 \mathrm{~V}$ for $2 e^{-}$
$\therefore \mathrm{E}_{\text {cell }}^{\circ}$ for $1 e^{-}=\frac{1.56}{2}=0.78 \mathrm{~V}$