While charging the lead storage battery,

In $H_2-O_2$ fuel cell,the reaction occurring at the cathode is:

If $6$ batteries are connected in series in a car,and each battery has a potential of $2 \ V$,what is the total voltage of the battery system (in $V$)?

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: $E^{\circ}_{Au^{3+}/Au} = +1.50 \ V, E^{\circ}_{Ca^{2+}/Ca} = -2.87 \ V, 1 \ F = 96500 \ C \ mol^{-1}$)

Give advantages of fuel cell.

In a fuel cell,$H_2$ and $O_2$ react to produce electricity. In this process,$H_2$ gas is oxidized at the anode and $O_2$ gas is reduced at the cathode. If $67.2 \ L$ of $H_2$ gas at $\text{STP}$ is consumed in $15 \ min$,what is the current produced (in $A$)?