Question

Does hydrogen undergoes reduction or oxidation on the basis of oxidation number in 2NH3 +H2SO4 which gives (NH4)SO4

Answer 1

neither. this is an acid/base neutralization reaction, and none of the species changes oxidation numbers. N is -3 on the left, and N is -3 on the right. S, O remain the same, as does H.

2NH3 + H2SO4 >> (NH4)2SO4