Which of the following metals will not release $H_{2(g)}$ upon reaction with an acid?

Calculate $E_{cell}^o$ of the following galvanic cell at $298 \ K$:
$Ca_{(s)} | Ca^{2+}_{(aq)} || Fe^{2+}_{(aq)} | Fe_{(s)}$
Given: $E_{Ca^{2+}/Ca}^o = -2.87 \ V$; $E_{Fe/Fe^{2+}}^o = 0.41 \ V$

The standard electrode potentials at $25\,^oC$ for the following half-reactions are given:
$Zn^{2+} + 2e^- \to Zn, E^o = -0.762\,V$
$Mg^{2+} + 2e^- \to Mg, E^o = -2.37\,V$
When zinc dust is added to a solution of $MgCl_2$,what happens?

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

The standard reduction potentials of $Zn^{2+}|Zn$,$Cu^{2+}|Cu$ and $Ag^{+}|Ag$ are respectively $-0.76 \ V$,$0.34 \ V$ and $0.80 \ V$. The following cells were constructed:
$(1)$ $Zn|Zn^{2+}||Cu^{2+}|Cu$
$(2)$ $Zn|Zn^{2+}||Ag^{+}|Ag$
$(3)$ $Cu|Cu^{2+}||Ag^{+}|Ag$
What is the correct order of $E_{\text{cell}}^{\circ}$ of these cells?

The standard hydrogen electrode has a zero electrode potential because .....