Which of the following has the least tendency to liberate $H_2$ from mineral acids?

Give the uses of the standard hydrogen electrode $(SHE)$.

The $EMF$ of a cell whose half-cell reactions are given below is .......... $V$.
$Mg^{2+} + 2e^- \to Mg_{(s)}; E^o = -2.37 \ V$
$Cu^{2+} + 2e^- \to Cu_{(s)}; E^o = +0.34 \ V$ (in $V$)

If standard reduction potential $(E^{\circ})$ of $(Ni_{(aq)}^{+2} \mid Ni_{(s)})$ and $(Al_{(aq)}^{+3} \mid Al_{(s)})$ are $-0.25 \ V$ and $-1.66 \ V$ respectively,what is the standard emf of the cell reaction $2 \ Al_{(s)} + 3 \ Ni_{(aq)}^{+2} \rightarrow 2 \ Al_{(aq)}^{+3} + 3 \ Ni_{(s)}$?

If the $E^{0}$ values for $Mg^{+2} | Mg$,$Zn^{+2} | Zn$,and $Fe^{+2} | Fe$ are $-2.37 \ V$,$-0.76 \ V$,and $-0.44 \ V$ respectively,which statement is correct?

Calculate the standard free energy change for the reaction $\frac{1}{2}Cu_{(s)} + \frac{1}{2}Cl_{2(g)} \rightleftharpoons \frac{1}{2}Cu^{2+} + Cl^-$ taking place at $25\ ^oC$ in a cell whose standard e.m.f. is $1.02 \ V$ (in $J$).