What are the uses of standard half-cell potential?

Consider the cell reaction at $300 \ K$: $A_{(s)} + B^{2+}_{(aq)} \rightleftharpoons A^{2+}_{(aq)} + B_{(s)}$. Its $E^{\circ}$ is $1.0 \ V$. The $\Delta_{r}H^{\circ}$ of the reaction is $-163 \ kJ \ mol^{-1}$. What is $\Delta_{r}S^{\circ}$ (in $J \ K^{-1} \ mol^{-1}$) of the reaction? $(F = 96500 \ C \ mol^{-1})$

At $298 \, K$, the standard Gibbs free energy of formation for $H_2O_{(l)}$, $CO_{2(g)}$, and $C_5H_{12(g)}$ are $-237.2$, $-394.4$, and $-8.2 \, kJ \, mol^{-1}$ respectively. What is the potential of a pentane-oxygen fuel cell in $V$?

Consider the following cell reaction:
$Cd_{(s)} + Hg_{2}SO_{4(s)} + \frac{9}{5}H_{2}O_{(l)} \rightleftharpoons CdSO_{4} \cdot \frac{9}{5}H_{2}O_{(s)} + 2Hg_{(l)}$
The value of $E_{\text{cell}}^{0}$ is $4.315 \ V$ at $25^{\circ}C$. If $\Delta H^{\circ} = -825.2 \ kJ \ mol^{-1}$,the standard entropy change $\Delta S^{\circ}$ in $J \ K^{-1} \ mol^{-1}$ is ........ . (Nearest integer) [Given: Faraday constant $= 96487 \ C \ mol^{-1}$]

For a spontaneous reaction,the $\Delta G$,equilibrium constant $K$,and $E_{Cell}^{o}$ will be respectively:

Which of the following is not correct?