Mark the false statement.

• A
  $A$. $A$ salt bridge is used to eliminate liquid junction potential.
• B
  $B$. The Gibbs free energy change,$\Delta G$ is related to electromotive force $(E)$,as $\Delta G = -nFE$.
• C
  $C$. The Nernst equation for single electrode potential is $E = E^o - \frac{RT}{nF} \ln a_{M^{n+}}$.
• D
  $D$. The efficiency of a hydrogen-oxygen fuel cell is $23 \%$.