Step 1: Understanding disproportionation.
Disproportionation is a reaction in which the same element undergoes both oxidation and reduction.
Step 2: Oxidation state of phosphorus.
In orthophosphorous acid (\(\mathrm{H_3PO_3}\)), phosphorus has oxidation state +3.
Step 3: Products formed.
Phosphorus is oxidised to +5 state in phosphoric acid (\(\mathrm{H_3PO_4}\)) and reduced to –3 state in phosphine (\(\mathrm{PH_3}\)).
Step 4: Conclusion.
Thus, the products are phosphoric acid and phosphine.