Which of the following metals cannot displace $H_2$ from acids or $H_2O$ from its compounds?

The standard electrode potentials for $Ag^{+}/Ag$,$Hg_2^{2+}/2Hg$,$Cu^{2+}/Cu$,and $Mg^{2+}/Mg$ are $0.80 \, V$,$0.79 \, V$,$0.34 \, V$,and $-2.37 \, V$ respectively. If an aqueous solution containing $1 \, M$ concentration of each of these metal ions is electrolyzed,what is the correct order of metal deposition at the cathode as the voltage is increased?

$A$ cell constructed by coupling a standard copper electrode and a standard magnesium electrode has an $emf$ of $2.7 \ V$. If the standard reduction potential of the copper electrode is $+0.34 \ V$,the standard reduction potential of the magnesium electrode is .............. $V$.

Which of the following has the highest electrode potential?

For the reaction $Cr_2O_7^{2-} + I^- \to I_2 + Cr^{3+}$,if $E_{cell}^o = 0.79 \ V$ and $E_{Cr_2O_7^{2-}}^o = 1.33 \ V$,then $E_{I_2}^o = $ ............. $V$.

If the emf of the cell $Cu(s) | Cu^{2+}(1M) || Ag^+(1M) | Ag(s)$ is $0.463 \text{ V}$ at $25^{\circ} \text{C}$ and the standard electrode potential of the $Cu$ electrode is $0.337 \text{ V}$, find the standard electrode potential of the $Ag$ electrode. (in $\text{ V}$)