Calculate the mass fraction of elements in the H2SO4 compounds.

Decision:
1. The relative atomic mass of hydrogen is 1, sulfur is 32, oxygen is 16.
2. Find the molecular weight of the compound:
2 * 1 + 32 + 16 * 4 = 98
3. Mass fraction of hydrogen is equal to:
1 * 2/98 = 2/98 = 0.0204 (2.04%)
4. Mass fraction of sulfur is equal to:
32/98 = 0.3265 (32.65%)
5. Mass fraction of oxygen is equal to:
4 * 16/98 = 64/98 = 0.6531 (65.31%)
Answer: the mass fraction of hydrogen is 2.04%, the mass fraction of sulfur is 32.65%, the mass fraction of oxygen is 65.31%.