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

The standard reduction potential for $Fe^{2+}/Fe$ and $Sn^{2+}/Sn$ electrodes are $-0.44 \ V$ and $-0.14 \ V$ respectively. For the given cell reaction $Fe^{2+} + Sn \to Fe + Sn^{2+}$,the standard $EMF$ is ...............$V$.

If $E^0_{Fe^{2+} / Fe} = -0.441 \ V$ and $E^0_{Fe^{3+} / Fe^{2+}} = 0.771 \ V$,the standard emf of the cell reaction $Fe_{(s)} + 2 Fe^{3+}_{(aq)} \longrightarrow 3 Fe^{2+}_{(aq)}$ is

$Mg^{2+}$ displaces hydrogen from acids but copper does not. $A$ galvanic cell prepared by combining $Cu/Cu^{2+}$ and $Mg/Mg^{2+}$ has an $EMF$ of $2.71 \ V$ at $298 \ K$. If the potential of copper electrode is $0.34 \ V$,what is the reduction potential of $Mg$ electrode?

Fill in the blanks :
$1$. ...... metal is the strongest reducing agent in aqueous solution.
$2$. ...... gas is the strongest oxidizing agent.
$3$. The standard reduction potential of any electrode is measured with reference to ......

The standard reduction potentials for two half-cell reactions are given below:
$Cd^{2+}_{(aq)} + 2e^{-} \rightarrow Cd_{(s)}, E^o = -0.40 \ V$
$Ag^{+}_{(aq)} + e^{-} \rightarrow Ag_{(s)}, E^o = 0.80 \ V$
What is the standard free energy change $\Delta G^o$ in $kJ$ for the reaction $2Ag^{+}_{(aq)} + Cd_{(s)} \rightarrow 2Ag_{(s)} + Cd^{2+}_{(aq)}$?