In sulphur estimation, 0.157 g of an organic compound gave 0.4813 g of barium sulphate. The percentage of sulphur in the compound is

Percentage of sulphur can be calculated by calculating the amount of sulphur present in the given amount of barium sulphate.
Molecular mass of BaSO₄ = 137 + 32+ 64 = 233 g
233 g BaSO₄  contains 32 g of sulphur
0.4813 g BaSo₄ contains $\frac{32 \times 0.4813}{233} \text{g of\hspace{0.17em}sulphur}$

Percentage of sulphur = $\frac{32 \times 0.4813 \times 100}{233 \times 0.157}=42.10 \%$