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

$Cu^{+} + e^- \to Cu$ ; $E^o = X_1 \ V$
$Cu^{2+} + 2e^- \to Cu$ ; $E^o = X_2 \ V$
Then for $Cu^{2+} + e^- \to Cu^{+}$ ; $E^o$ will be ?

Given:
$Fe^{3+}_{(aq)} + e^- \to Fe^{2+}_{(aq)}; E^o = +0.77 \ V$
$Al^{3+}_{(aq)} + 3e^- \to Al_{(s)}; E^o = -1.66 \ V$
$Br_{2(aq)} + 2e^- \to 2Br^-_{(aq)}; E^o = +1.09 \ V$
Considering the electrode potentials,which of the following represents the correct order of reducing power?

What is the value of the standard electrode potential of a standard hydrogen electrode $(SHE)$ (in $V$)?

At $25^\circ C$,$1 \, atm$ of gas $X$ is bubbled through a solution containing $1 \, M$ $Y^-$ and $1 \, M$ $Z^-$. If the reduction potential order is $Z > Y > X$,then:

Which of the following metals will not evolve $H_2$ gas from dilute $H_2SO_4$ solution?