The $E^o$ values of $Mg^{2+}/Mg$ is $-2.37 \ V$,$Zn^{2+}/Zn$ is $-0.76 \ V$,and $Fe^{2+}/Fe$ is $-0.44 \ V$. Which of the following statements is correct?

Which one of the following metals cannot evolve $H_2$ from acids,$H_2O$,or from its compounds?

Given $E^{\circ} Mn^{7+} / Mn^{2+} = 1.51 \ V$ and $E^{\circ} Mn^{4+} / Mn^{2+} = 1.23 \ V$. Calculate $E^{\circ} Mn^{7+} / Mn^{4+}$. (in $V$)

For four metals $A, B, C$ and $D$,the standard reduction potentials are $-3.05 \ V, -1.66 \ V, -0.40 \ V$ and $0.80 \ V$ respectively. Which metal exhibits the highest chemical reactivity?

The cell potential of a cell in operation is

$MnO_4^- (aq) + 8H^+ (aq) + 5e^- \to Mn^{2+} (aq) + 4H_2O (l)$; $E_1^o = 1.51 \ V$
$MnO_2 (s) + 4H^+ (aq) + 2e^- \to Mn^{2+} (aq) + 2H_2O (l)$; $E_2^o = 1.21 \ V$
$MnO_4^- (aq) + 4H^+ (aq) + 3e^- \to MnO_2 (s) + 2H_2O (l)$; $E_3^o = ?$
Value of $E_3^o$ will be ............ $V$