Question

Why is concentrated sulphuric acid called H2SO4 when sulphur is S8

Answer 1

Concentrated nitric acid acts as an oxidizing agent for both sulfur & carbon. In the case of sulfur, S will get the oxygen atoms & the water needed for the reaction:

S + 6HNO3 → H2SO4 + 2H2O + 6NO2

so if sulfur is converted to SO2 first, it will proceed into SO3 & eventually to H2SO4.