Which metal does not give the following reaction? $M + \text{water} \rightarrow \text{oxide or hydroxide} + H_2$

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 $V$)

The standard electrode potential is measured by

The cell potential of the given cell is $0.34 \, V$. Write the cell reaction and calculate $E^o_{Cu^{2+}|Cu}$.
$Pt_{(s)} \mid H_{2(g)} (1 \, bar) \mid H^+_{(1 \, M)} \parallel Cu^{2+}_{(1 \, M)} \mid Cu_{(s)}$

The standard Gibbs energy change for the Daniel cell reaction is $Zn_{(s)} + Cu^{2+}_{(aq)} \longrightarrow Zn^{2+}_{(aq)} + Cu_{(s)}$ where $E_{\text{cell}}^{\circ} = 1.1 \ V$.

The standard cell potential of a cell consisting of copper and $Mg$ standard half-cells is $2.7 \ V$. If the standard reduction potential of the copper electrode is $+0.34 \ V$,what is the standard reduction potential of the magnesium electrode in volts?