What is the sign of $\Delta G^o$ and the value of $K$ for an electrochemical cell for which $E_{cell}^o = 0.80 \ V$?

What will be the electromotive force of the following cell $Fe|Fe^{+2}\,(0.2\, M)\,||\, Au^{+3}\,(0.02\, M)\,|Au$ (in $,V$)?
Given: $E^o_{Fe^{+2}/Fe} = -0.44\,V$ and $E^o_{Au^{+3}/Au} = +1.50\,V$.

The standard $e.m.f.$ of a cell involving a one-electron change is found to be $0.591 \ V$ at $25^{\circ} C$. What is the equilibrium constant for the reaction? $(F = 96500 \ C \ mol^{-1}; R = 8.314 \ J \ K^{-1} \ mol^{-1})$

The potential of the cell for the reaction $M_{(s)} + 2H^{+}(1 \ M) \to H_2(1 \ atm) + M^{2+}(0.1 \ M)$ is $1.5 \ V$. The standard reduction potential for $M^{2+}/M_{(s)}$ couple is ............. $V$.

What will be the electromotive force of the following cell at $298 \ K$ ............. $V$
$Pt \, | \, Br_{2(\ell), 0.1M} \, | \, Br^{-}_{(aq), 0.1M} \, || \, H^{+}_{(aq), 0.1M} \, | \, H_{2(g), 1atm} \, | \, Pt$
Given: $E^{0}_{Br^{-}/Br_{2}} = -1.06 \ V$

Calculate the equilibrium constant for the following reaction: $Ni_{(s)} + Cu_{(aq)}^{2+} \to Cu_{(s)} + Ni_{(aq)}^{2+}$. Given: $E_{Ni^{2+}|Ni}^o = -0.25 \ V$ and $E_{Cu^{2+}|Cu}^o = 0.34 \ V$.