If $Cu^{+} + e^- \to Cu$ ; $E^o = X_1$ and $Cu^{2+} + 2e^- \to Cu$ ; $E^o = X_2$,then the value of $E^o$ for $Cu^{2+} + e^- \to Cu^{+}$ will be:

The standard reduction electrode potentials of four metals are $A = -0.250 \ V$,$B = -0.140 \ V$,$C = -0.126 \ V$,and $D = -0.402 \ V$. Which metal can displace $A$ from its aqueous salt solution?

For the half-cell $Zn^{2+} | Zn$,the standard electrode potential $E^{\circ}$ is $-0.76 \ V$. What is the $e.m.f.$ of the cell $Zn_{(s)} | Zn^{2+}_{(aq)} (1 \ M) || 2H^{+}_{(aq)} (1 \ M) | H_{2(g)} (1 \ atm)$ in $V$?

The standard reduction potentials at $25^o C$ are given below. Which is the strongest reducing agent?
$Zn^{2+}_{(aq)} + 2e^{-} \rightleftharpoons Zn_{(s)}$,$E^o_{RP} = -0.762 \, V$
$Cr^{3+}_{(aq)} + 3e^{-} \rightleftharpoons Cr_{(s)}$,$E^o_{RP} = -0.740 \, V$
$2H^{+}_{(aq)} + 2e^{-} \rightleftharpoons H_{2(g)}$,$E^o_{RP} = 0.00 \, V$
$Fe^{3+}_{(aq)} + e^{-} \rightleftharpoons Fe^{2+}_{(aq)}$,$E^o_{RP} = 0.77 \, V$

Give the anode reaction for an electrode of any metal $M \,|\, M^{n+}$.

Arrange the following metals in the order in which they displace each other from the solution of their salts: $Al, Cu, Fe, Mg$ and $Zn$.