What is "h3po2"

Hypophosphorous \Hy`po*phos"phor*ous\, a. [Pref. hypo- + phosphorous.] (Chem.) Pertaining to, or containing, phosphorus in a lower state of oxidation than in phosphoric compounds; as, hypophosphorous acid.

Hypophosphorous acid (Chem.), an acid, H3PO2, whose salts are produced by the action of barium hygrate on phosphorus. It may be obtained from its water solution, by exaporation and freezing, as a white crystalline substance. It is a powerful reducing agent.