Suggest two materials other than hydrogen that can be used as fuels in fuel cells.

In a $Cu-Zn$ cell,.....

When a $Cu$ rod is kept in an $AgNO_3$ solution,what is the redox reaction that occurs?

Based on the reaction $\frac{4}{3} \, Al + O_2 \to \frac{2}{3} \, Al_2O_3$,with $\Delta G = -827 \, kJ \, mol^{-1}$ of $Al_2O_3$,what is the minimum $e.m.f.$ required for the electrolysis? $(F = 96500 \, C \, mol^{-1})$

The standard free energy change $(\Delta G^{\circ})$ for the following reaction (in $kJ$) at $25^{\circ} C$ is $3 Ca_{(s)} + 2 Au^{3+}(aq, 1 M) \rightarrow 3 Ca^{2+}(aq, 1 M) + 2 Au_{(s)}$ (given: $E^{\circ}_{Au^{3+}/Au} = +1.50 \ V, E^{\circ}_{Ca^{2+}/Ca} = -2.87 \ V, 1 \ F = 96500 \ C \ mol^{-1}$)

At the anode,the process of $......$ occurs,and at the cathode,the process of $......$ occurs.