During electrolysis of conc. H2SO4, perdisulphuric acid (H2S2O8), and O2
form in equimolar amount. The amount of H2 that will form simultaneously will be :
1. Thrice that of O2 in moles.
2. Twice that of O2 in moles.
3. Equal to that of O2 in moles.
4. Half of that of O2 in moles.