For the feasibility of a redox reaction in a cell,the e.m.f. should be

The standard electrode potentials are: $K^{+}/K = -2.93 \ V$,$Ag^{+}/Ag = 0.80 \ V$,$Hg^{2+}/Hg = 0.79 \ V$,$Mg^{2+}/Mg = -2.37 \ V$,$Cr^{3+}/Cr = -0.74 \ V$. Arrange these metals in the increasing order of their reducing power.

$A$ standard hydrogen electrode has zero electrode potential because

What is the relationship between Gibbs free energy of the cell reaction in a galvanic cell and the emf of the cell? When will the maximum work be obtained from a galvanic cell?

For the cell reaction,$2 Al_{(s)} + 3 Cu^{2+}_{(aq)} \rightarrow 2 Al^{3+}_{(aq)} + 3 Cu_{(s)}$. If $\Delta G^{\circ} = -1158 \ kJ$,what is $E^{\circ}_{cell}$ (in $V$)?

$FeO_4^{2-}$ $\xrightarrow{2.2 \ V} Fe^{3+}$ $\xrightarrow{0.70 \ V} Fe^{2+}$ $\xrightarrow{-0.45 \ V} Fe^0$
$E_{FeO_4^{2-} / Fe^{2+}}^{\theta}$ is $x \times 10^{-3} \ V$. The value of $x$ is $.........$.