If $E^0_{Fe^{2+} / Fe} = -0.441 \ V$ and $E^0_{Fe^{3+} / Fe^{2+}} = 0.771 \ V$,the standard emf of the cell reaction $Fe_{(s)} + 2 Fe^{3+}_{(aq)} \longrightarrow 3 Fe^{2+}_{(aq)}$ is

For the reduction of $NO_3^{-}$ ion in an aqueous solution,$E^0$ is $+0.96 \ V$. Values of $E^0$ for some metal ions are given below:
$V^{2+}_{(aq)} + 2e^{-} \rightarrow V \ \ \ \ E^0 = -1.19 \ V$
$Fe^{3+}_{(aq)} + 3e^{-} \rightarrow Fe \ \ \ \ E^0 = -0.04 \ V$
$Au^{3+}_{(aq)} + 3e^{-} \rightarrow Au \ \ \ \ E^0 = +1.40 \ V$
$Hg^{2+}_{(aq)} + 2e^{-} \rightarrow Hg \ \ \ \ E^0 = +0.86 \ V$
The pair$(s)$ of metals that is(are) oxidized by $NO_3^{-}$ in aqueous solution is(are):
$(A) V$ and $Hg$
$(B) Hg$ and $Fe$
$(C) Fe$ and $Au$
$(D) Fe$ and $V$

In which metal container can an aqueous solution of $CuSO_4$ be stored?
$E^0_{Cu^{2+}/Cu} = 0.34 \ V$,$E^0_{Fe/Fe^{2+}} = 0.44 \ V$,$E^0_{Al/Al^{3+}} = 1.66 \ V$,$E^0_{Ni/Ni^{2+}} = 0.25 \ V$,$E^0_{Ag^{+}/Ag} = 0.80 \ V$

What is the standard reduction potential of $Cu^{2+} \mid Cu_{(s)}$ if the $E^{\circ}$ of the following cell is $0.46 \ V$ (in $V$)?
$Cu_{(s)} \mid Cu_{(aq)}^{2+} \parallel Ag_{(aq)}^{+} \mid Ag_{(s)}$ ; $E_{Ag^{+} / Ag}^{\circ} = 0.80 \ V$

$A$ galvanic cell consists of a copper electrode and a standard hydrogen electrode. If $E^\circ (Cu^{2+}_{(aq)} | Cu_{(s)}) = +0.34 \text{ V}$, identify the reaction taking place at the positive electrode during the working of the cell.

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