The specific conductance $\left(\mathrm{K}\right)$ of $0.02 \mathrm{M}$ aqueous acetic acid solution at $298 \mathrm{K}$ is $1.65\times {10}^{-4} \mathrm{S} {\mathrm{cm}}^{-1}$. The degree of dissociation of acetic acid is [Given: equivalent conductance at infinite dilution of ${\mathrm{H}}^{+}=349.1 {\mathrm{cm}}^2 {\mathrm{mol}}^{-1}$ and ${\mathrm{CH}}_3{\mathrm{COO}}^{-}=40.9 {\mathrm{S}}^2 {\mathrm{cm}}^2 {\mathrm{mol}}^{-1}$ ].

From the following ${\mathrm{E}}^0$ values of half cells

${\mathrm{A}}^{3-}\to {\mathrm{A}}^{2-}+{\mathrm{e}}^{-}; {\mathrm{E}}^0=1.5 \mathrm{V}$

${\mathrm{B}}^{+}+{\mathrm{e}}^{-}\to \mathrm{B}; {\mathrm{E}}^0=-0.5 \mathrm{V}$

${\mathrm{C}}^{2+}+{\mathrm{e}}^{-}\to {\mathrm{C}}^{+}; {\mathrm{E}}^0=+0.5 \mathrm{V}$

$\mathrm{D}\to {\mathrm{D}}^{2+}+2{\mathrm{e}}^{-}; {\mathrm{E}}^0=-1·5 \mathrm{V}$

What combination of two half cells would result in a cell with the largest potential?

$50 \mathrm{mL}$ of hydrogen gas was collected over at $23°\mathrm{C}, 740 \mathrm{mmHg}$ barometric pressure. ${\mathrm{H}}_2$ was produced by the electrolysis of water. The voltage was constant at $2.1$ $\mathrm{volts}$, the current averaged $0.50 \mathrm{amp}$ for $12 \mathrm{minutes}$ and $20 \mathrm{seconds}$. Calculate the Avogadro's constant. 

Divide the answer by $1\times {10}^{23}$ and give the answer up to two places of decimal.