What is the chemical reaction that occurs during the discharging of a lead storage cell?

Efficiency of a cell with cell reaction under standard conditions is $70\%$. Cell reaction:
$A_{(s)} + B^{\oplus} \longrightarrow A^{\oplus} + B_{(s)}$ ; $\Delta H^o = -551.5 \ kJ$. Calculate standard electrode potential of cell (in $volt$).

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.
$[E^{o}_{Zn^{2+}\mid Zn} = -0.76 \ V, E^{o}_{Ag_{2}O\mid Ag} = 0.34 \ V]$

What is the correct expression for $\Lambda_{m(NH_4OH)}^0$?

Litharge is $NOT$ commonly used in which of the following?

Standard electrode potentials of $Zn$ and $Fe$ are known to be $(i) -0.76 \ V$ and $(ii) -0.44 \ V$ respectively. How does this explain that galvanization prevents rusting of iron while zinc slowly dissolves away?