Which of the following changes takes place at the positive electrode during the working of a dry cell?

While charging the lead storage battery,

The following reaction occurs in a button cell:
$(i)$ $Ag_{2}O + H_{2}O + 2e^{-} \rightarrow 2Ag + 2OH^{-}$
$(ii)$ $Zn \rightarrow Zn^{2+} + 2e^{-}$
Calculate the standard Gibbs free energy change $\Delta G^{o}$ for the overall cell reaction.
$[E^{o}_{Zn^{2+}\mid Zn} = -0.76 \ V, E^{o}_{Ag_{2}O\mid Ag} = 0.34 \ V]$

An electrochemical cell can behave like an electrolytic cell when . . . . . . .

In which cell is the free energy of a chemical reaction directly converted into electricity?

The Gibbs energy for the decomposition of $Al_2O_3$ at $500\,^oC$ is as follows:
$\frac{2}{3}Al_2O_3 \to \frac{4}{3}Al + O_2, \Delta_rG = +940\,kJ\,mol^{-1}$
The potential difference needed for the electrolytic reduction of aluminium oxide is ............... $V$.