Question

in eletrolysics of water if H2SO4 is not present so what ehoud happen​

Answer 1

Well, the simplest answer is "electrolysis process will remain slow". ... The self-ionization of water is the main reason for electrolysis. But, the conductivity of water remains low. Addition of sulfuric acid causes an increase in conductivity.

Answer 2

Most people wouldn’t use H2SO4 as an electrolyte because it’ll corrode your equipment faster than most of the alternative chemicals, but it’s in there to improve the water’s ability to conduct electricity. Depending on how pure the water is, not adding an electrolyte to the water will either greatly slow the process or keep it from happening at all.