Which electrode is used to measure the electrode potential of any electrode?

If $E^{\circ}(Fe^{+2}_{(aq)} \mid Fe_{(s)}) = -0.44 \ V$ and $E^{\circ}(Sn^{+2}_{(aq)} \mid Sn_{(s)}) = -0.14 \ V$,what is the standard $emf$ of the cell containing the two electrodes?

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

$A$ galvanic cell consists of a copper electrode and a standard hydrogen electrode. If $E^0_{(Cu^{2+}(aq)|Cu(s))} = +0.34 \text{ V}$, identify the reaction taking place at the positive electrode during the working of the cell.

The standard reduction potentials at $298 \ K$ for the following half-reactions are given:
$Zn^{2+}_{(aq)} + 2e^- \rightleftharpoons Zn_{(s)}; E^\circ = -0.762 \ V$
$Cr^{3+}_{(aq)} + 3e^- \rightleftharpoons Cr_{(s)}; E^\circ = -0.740 \ V$
$2H^+_{(aq)} + 2e^- \rightleftharpoons H_{2(g)}; E^\circ = 0.00 \ V$
$Fe^{3+}_{(aq)} + e^- \rightleftharpoons Fe^{2+}_{(aq)}; E^\circ = 0.770 \ V$
Which is the strongest reducing agent?

Standard electrode potential values,$E^{\Theta}$ for $Al^{3+}/Al$ is $-1.66 \ V$ and that of $Tl^{3+}/Tl$ is $+1.26 \ V$. Predict the formation of $M^{3+}$ ion in solution and compare the electropositive character of the two metals.