Consider the following electrochemical cellin
$$
\mathrm{Pt}\left|\mathrm{O}_2(\mathrm{~g})(\mathrm{lbar})\right| \mathrm{HCl}(\mathrm{aq}) \| \mathrm{M}^{2+}(\mathrm{aq}, 1.0 \mathrm{M}) \mid \mathrm{M}(\mathrm{~s})
$$
The pH above which, oxygen gas would start to evolve at anode is $\_\_\_\_$ (nearest integer).
Given:
$$
\left.\begin{array}{l}
\mathrm{E}_{\mathrm{M}^{2+} / \mathrm{M}}^{\mathrm{o}}=0.994 \mathrm{~V} \\
\mathrm{E}_{\mathrm{O}_2 / \mathrm{H}_2 \mathrm{O}}^{\mathrm{o}}=1.23 \mathrm{~V}
\end{array}\right\} \text { standard reduction potential }
$$
and $\frac{\mathrm{RT}}{\mathrm{F}}(2.303)=0.059 \mathrm{~V}$ at the given condition
