The cell potential for the given cell at 298 K Pt | H_2( g, 1 bar )| H^+( aq ) ∥ Cu^2+( aq ) ∣ Cu ( s ) is 0.31 V. The pH of the acidic solution is…

The cell potential for the given cell at $\displaystyle 298$ K $$\mathrm{Pt}\left|\mathrm{H}_2(\mathrm{~g}, 1 \mathrm{bar})\right| \mathrm{H}^{+}(\mathrm{aq}) \| \mathrm{Cu}^{2+}(\mathrm{aq}) \mid \mathrm{Cu}(\mathrm{~s}) $$ is $\displaystyle 0.31$ V . The pH of the acidic solution is found to be $\displaystyle 3$ , whereas the concentration of $\displaystyle \mathrm{Cu}^{2+}$ is $\displaystyle 10^{-x} \mathrm{M}$. The value of $\displaystyle x$ is \_\_\_\_. (Given: $\displaystyle \mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\ominus}=0.34 \mathrm{~V}$ and $\displaystyle \frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.06 \mathrm{~V}$ )