Question
0.5 g of an organic substance containing phosphorous was heated with conc. HNO3 in the Carius tube. The phosphoric acid thus formed was precipitated with magnesia mixture, (MgNH4PO4), which on ignition gave a residue of 1.0 g of magnesium pyrrophosphate (Mg2P2O7). The percentage of phosphorous in the organic compound is :