Consider the cell
$$
\mathrm{Pt}_{(\mathrm{s})}\left|\mathrm{H}_2(\mathrm{~g}, 1 \mathrm{~atm})\right| \mathrm{H}^{+}(\mathrm{aq}, 1 \mathrm{M})| | \mathrm{Fe}^{3+}(\mathrm{aq}), \mathrm{Fe}^{2+}(\mathrm{aq}) \mid \mathrm{Pt}(\mathrm{~s})
$$
When the potential of the cell is 0.712 V at 298 K , the ratio $\left[\mathrm{Fe}^{2+}\right] /\left[\mathrm{Fe}^{3+}\right]$ is $\_\_\_\_$ .
(Nearest integer) Given: $\mathrm{Fe}^{3+}+\mathrm{e}^{-}=\mathrm{Fe}^{2+}, \mathrm{E}^{\circ} \mathrm{Fe}^{3+}, \mathrm{Fe}^{2+} \mid \mathrm{Pt}=0.771$
$$
\frac{2.303 R T}{F}=0.06 \mathrm{~V}
$$
