SECTION VI - PRODUCTS OF THE CHEMICAL OR ALLIED INDUSTRIES > CHAPTER 28 - INORGANIC CHEMICALS; ORGANIC OR INORGANIC COMPOUNDS OF PRECIOUS METALS, OF RARE-EARTH METALS, OF RADIOACTIVE ELEMENTS OR OF ISOTOPES > II. INORGANIC ACIDS AND INORGANIC OXYGEN COMPOUNDS OF NON-METALS > 2809 Diphosphorus pentaoxide; phosphoric acid; polyphosphoric acids, whether or not chemically defined > Diphosphorus pentaoxide