What is Nernst equation ? Write the equation for an electrode with electrode reaction
${\mathrm{M}}^{\mathrm{n}+}\left(\mathrm{aq}\right)+{\mathrm{ne}}^{-}\rightleftharpoons \mathrm{M}\left(\mathrm{s}\right)$

The equation that gives the dependence of the electrode potential on the concentration of ions with which this electrode is reversible is known as Nernst equation.
Nernst equation for metal electrodes (or) Hydrogen:
$\begin{array}{l}{\mathrm{M}}_{\left(\mathrm{aq}\right)}^{\mathrm{n}+}+{\mathrm{ne}}^{-}\rightleftharpoons {\mathrm{M}}_{\left(\mathrm{s}\right)}\\ \mathrm{E}={\mathrm{E}}^{\mathrm{o}}+\frac{2.303\mathrm{RT}}{\mathrm{nF}}\log \mathrm{c}\text{ (or) }\mathrm{E}={\mathrm{E}}^{\mathrm{o}}+\frac{0.0591}{\mathrm{n}}\log \mathrm{c}\end{array}$