Which of the following chemical reaction occur at anode during electrolysis of higher concentrated H2SO4 solution?
1
\(2 \mathrm{SO}_{4_{(\mathrm{aq})}}^{2-} \rightarrow \mathrm{S}_{2} \mathrm{O}_{8_{(\mathrm{aq})}}^{2-}+2 \mathrm{e}^{-}\)
2
\(\rm 2 \mathrm{H}_{2} \mathrm{O}_{(l)} \rightarrow \mathrm{O}_{2_{(\mathrm{g})}}+4 \mathrm{H}_{(\mathrm{aq})}^{+}+4 \mathrm{e}^{-}\)
3
\(\rm \mathrm{H}_{2} \mathrm{O}_{(l)}+\mathrm{e}^{-} \rightarrow \frac{1}{2} \mathrm{H}_{2_{(\mathrm{g})}}+2 \mathrm{OH}_{(\mathrm{aq})}^{-}\)
4
\(\mathrm{S}_{2} \mathrm{O}_{8_{(\mathrm{aq}})}^{2-}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{SO}_{4_{(\mathrm{aq})}}^{2-}\)