Which one among the following is the strongest reducing agent?
$Fe^{2+} + 2e^- \to Fe \ (E^\circ = -0.44 \ V)$
$Ni^{2+} + 2e^- \to Ni \ (E^\circ = -0.25 \ V)$
$Sn^{2+} + 2e^- \to Sn \ (E^\circ = -0.14 \ V)$
$Fe^{3+} + e^- \to Fe^{2+} \ (E^\circ = +0.77 \ V)$

If standard reduction potential $(E^{\circ})$ of $(Ni_{(aq)}^{+2} \mid Ni_{(s)})$ and $(Al_{(aq)}^{+3} \mid Al_{(s)})$ are $-0.25 \ V$ and $-1.66 \ V$ respectively,what is the standard emf of the cell reaction $2 \ Al_{(s)} + 3 \ Ni_{(aq)}^{+2} \rightarrow 2 \ Al_{(aq)}^{+3} + 3 \ Ni_{(s)}$?

Given
$E^o_{Cl_2/Cl^-} = 1.36 \ V,$
$E^o_{Cr^{3+}/Cr} = -0.74 \ V,$
$E^o_{Cr_2O_7^{2-}/Cr^{3+}} = 1.33 \ V,$
$E^o_{MnO_4^-/Mn^{2+}} = 1.51 \ V$
Among the following,the strongest reducing agent is:

For the following cell reaction,$Ag | Ag^{+} | AgCl | Cl^{-} | Cl_2, Pt$
$\Delta G_f^{\circ}(AgCl) = -109 \ kJ/mol$
$\Delta G_f^{\circ}(Cl^{-}) = -129 \ kJ/mol$
$\Delta G_f^{\circ}(Ag^{+}) = 78 \ kJ/mol$
$E^{\circ}$ of the cell is

The electrode potentials for $Cu^{2+}_{(aq)} + e^- \rightarrow Cu^{+}_{(aq)}$ and $Cu^{+}_{(aq)} + e^- \rightarrow Cu_{(s)}$ are $+0.15 \ V$ and $+0.50 \ V$ respectively. The value of $E^o_{Cu^{2+}/Cu}$ will be $........ \ V$.

Which of the following equations represents the cell potential?