which oxyacid of phosphorus has a tendency to show higher and lower Oxidation State

Dear Student, 
Hypophosphorus acid, H₃PO₂ can show both higher and lower oxidation state, as in this oxoacid it is in +3 oxidation state and thus it can go to both +3(H₃PO₃) and
​​​​​​-3(PH₃) oxidation state. 

Regards.