Calculate the mass percentage of sulphur in sulphuric acid, H2SO4. (Atomic masses: H = 1, S = 32, O = 16)

1. Molecular mass of H2SO4 $= (1 \times 2) + (32 \times 1) + (16 \times 4) = 2 + 32 + 64 = 98$ g. 2. Mass % of S $= \dfrac{32}{98} \times 100$. 3. $= 32.65\%$. The value $65.31\%$ is the mass percentage of oxygen, not sulphur. _Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 7 Atoms and Molecules "Percent Composition", p.109_