The values of $E^0$ for metals $A$,$B$,and $C$ are $0.34 \ V$,$-0.80 \ V$,and $-0.46 \ V$ respectively. State the correct order for their ability to act as reducing agents.

Given the standard reduction potentials at $25\,^oC$ for the following half-reactions:
$Zn^{2+}_{(aq)} + 2e^- \rightleftharpoons Zn_{(s)}, E^o = -0.76\,V$
$Cr^{3+}_{(aq)} + 3e^- \rightleftharpoons Cr_{(s)}, E^o = -0.74\,V$
$2H^+_{(aq)} + 2e^- \rightleftharpoons H_{2(g)}, E^o = 0.00\,V$
$Fe^{3+}_{(aq)} + e^- \rightleftharpoons Fe^{2+}_{(aq)}, E^o = +0.77\,V$
Which of the following is the strongest reducing agent?

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 electrode potential for the half-cell reactions are
$Zn^{2+} + 2e^{-} \longrightarrow Zn ; E^{\circ} = -0.76 \ V$
$Fe^{2+} + 2e^{-} \longrightarrow Fe ; E^{\circ} = -0.44 \ V$
The $emf$ of the cell reaction,
$Fe^{2+} + Zn \longrightarrow Zn^{2+} + Fe$ is

Standard reduction electrode potentials of three metals $A$,$B$,and $C$ are respectively $+0.5 \ V$,$-3.0 \ V$,and $-1.2 \ V$. The reducing powers of these metals are

Given,the standard potentials $E_{(Cu^{2+}/Cu)}^{\circ}$ and $E_{(Cu^{+}/Cu)}^{\circ}$ as $0.340 \ V$ and $0.522 \ V$ respectively,the value of $E_{(Cu^{2+}/Cu^{+})}^{\circ}$ is $.... \ V$