The standard reduction potentials for $Zn^{2+}/Zn$,$Ni^{2+}/Ni$ and $Fe^{2+}/Fe$ are $-0.76 \ V$,$-0.23 \ V$ and $-0.44 \ V$ respectively.
The reaction $X + Y^{2+} \rightarrow X^{2+} + Y$ will be spontaneous when:

The standard $E^{\circ}_{red}$ values of $A, B$ and $C$ are $+0.68 \ V, -2.54 \ V$ and $-0.50 \ V$ respectively. The order of their reducing power is:

How would you determine the standard electrode potential of the system $Mg^{2+} | Mg$?

Consider the following:
$Zn^{2+} + 2e^- \longrightarrow Zn_{(s)} ; E^o = -0.76 \, V$
$Ca^{2+} + 2e^- \longrightarrow Ca_{(s)} ; E^o = -2.87 \, V$
$Mg^{2+} + 2e^- \longrightarrow Mg_{(s)} ; E^o = -2.36 \, V$
$Ni^{2+} + 2e^- \longrightarrow Ni_{(s)} ; E^o = -0.25 \, V$
The reducing power of the metals increases in the order:

Electrode potentials of five elements $A, B, C, D$ and $E$ are respectively $-1.36 \ V, -0.32 \ V, 0 \ V, -1.26 \ V$ and $-0.42 \ V$. The reactivity order of these elements is:

If the standard potential of the electrochemical cell for the reaction $2Ag_{(aq)}^+ + Cd_{(s)} \to Cd_{(aq)}^{2+} + 2Ag_{(s)}$ is $1.20 \ V$,calculate the standard Gibbs free energy change in $kJ$.