Given, Mass of an organic compound =0.20 g Mass of AgBr=0.12 g Molecular mass of AgBr=188 gmol−1188 g of AgBr contains 80 g of bromine ∴0.12 g of AgBr will contain =18880​×0.12=0.05 g of bromine ∴ Percentage of bromine =0.200.05​×100=25%