The number of incorrect statement from the following is ……….
A. The electrical work that a reaction can perform at constant pressure and temperature is equal to the reaction Gibbs energy 

B. ${\mathrm{E}}_{\mathrm{cell}}^{\mathrm{o}}$ is dependent on the pressure
$\text{C. }\frac{{\mathrm{dE}}_{\text{cell }}^{\circ }}{\mathrm{dT}}=\frac{{\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{S}}^{\circ }}{\mathrm{nF}}$
D. A cell is operating reversibly if the cell potential is exactly balanced by an opposing source of potential difference