What is the oxidation and reduction potential of standard hydrogen electrode?

Discuss the method to determine the cell potential of any cell when a standard hydrogen electrode is considered as the anode,with a suitable example.

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 $2Ag^{+}_{(aq)} + Cd_{(s)} \rightarrow 2Ag_{(s)} + Cd^{2+}_{(aq)}$?

$E^o$ values for the half-cell reactions are given below:
$Cu^{2+} + e^- \to Cu^{+} \quad E^o = 0.15 \ V$
$Cu^{2+} + 2e^- \to Cu \quad E^o = 0.34 \ V$
What will be the $E^o$ for the half-cell reaction:
$Cu^{+} + e^- \to Cu$ ? $\dots \ V$

Which reference electrode is used to measure the electrode potential of other electrodes?

Standard electrode potential of three metals $X$,$Y$ and $Z$ are $-1.2 \, V$,$+0.5 \, V$ and $-3.0 \, V$ respectively. The reducing power of these metals will be