What is the potential of the cell containing two hydrogen electrodes as represented below $V$:
$Pt | \frac{1}{2} H_{2(g)} | H^{+} (10^{-8} M) || H^{+} (10^{-3} M) | \frac{1}{2} H_{2(g)} | Pt$

The $emf$ of cell $Tl | Tl^+_{(0.001M)} || Cu^{2+}_{(0.01M)} | Cu$ is $0.83 \ V$ at $298 \ K$. It could be increased by:

For the cell $Zn | Zn^{2+}_{(aq)} || Cu^{2+}_{(aq)} | Cu$,the standard cell potential $E^o$ is $1.10 \ V$ at $25^o \ C$. What is the order of magnitude of the equilibrium constant $K$ for the reaction $Zn + Cu^{2+}_{(aq)} \rightleftharpoons Cu + Zn^{2+}_{(aq)}$?

$E_{1}, E_{2}, E_{3}$ are the $EMF$ values of three galvanic cells with the reaction $Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)$ at $298 \ K$ with different concentrations: $(I) [Zn^{2+}] = 1 \ M, [Cu^{2+}] = 0.1 \ M$; $(II) [Zn^{2+}] = 1 \ M, [Cu^{2+}] = 1 \ M$; $(III) [Zn^{2+}] = 0.1 \ M, [Cu^{2+}] = 1 \ M$. Compare the $EMF$ values.

What is $E_{cell}$ (in $V$) of the following cell at $298 \ K$ ?
$(E^{\ominus}_{Zn^{2+}/Zn} = -0.76 \ V ; E^{\ominus}_{Ni^{2+}/Ni} = -0.25 \ V ; \frac{2.303 RT}{F} = 0.06 \ V)$
$Zn_{(s)} | Zn^{2+} (0.01 \ M) || Ni^{2+} (0.1 \ M) | Ni_{(s)}$

The cell reaction involving the quinhydrone electrode is given by the following equation:
$C_6H_4(OH)_2 \rightleftharpoons C_6H_4O_2 + 2H^+ + 2e^-$,$E^{\circ} = 1.30 \ V$
What will be the electrode potential at $pH = 3$ (in $V$)?