Select the incorrect statement about standard  hydrogen electrode.

• A

  ${\mathrm{H}}^{+}\left(\mathrm{aq}\right)\left|{\mathrm{H}}_2\left(\mathrm{g}\right)\right|\mathrm{Pt}\left(\mathrm{s}\right)$

• B

  $\frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right)\to {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{e}}^{-}$

• C

  fhe electrode is dipped in basic solution and pure hydrogen gas is butbled through it

• D

  Concentration of both the oxidised and reduced forms of hydrogen is maintained at unity