7.15 Give the disproportionation reaction of H3PO3.

On heating, orthophosphorus acid (H3PO3) disproportionates to give orthophosphoric acid (H3PO4) and phosphine (PH3). The oxidation states of P in various species involved in the reaction are mentioned below.

   4H3P+3O23H3P+5O4+PH3