The oxoacid of phosphorus having the strongest reducing property is

Step-by-step solution

The extent of reducing property is determined by the oxidation state of central atom. More is the oxidation state lesser will be the reducing property. The oxidation states of P in given oxoacids are as follows: (i) H 3 PO 3 3 + 1 + x + 3 - 2 = 0 3 + x - 6 = 0 x = + 3 (ii) H 3 PO 2 3 + 1 + x + 2 - 2 = 0 3 + x - 4 = 0 x = + 1 (iii) H 3 PO 4 3 + 1 + x + 4 - 2 = 0 3 + x - 8 = 0 x = + 5 (iv) H 4 P 2 O 7 4 + 1 + 2 x + 7 - 2 = 0 4 + 2 x - 14 = 0 x = + 5 As the oxidation state of P is least in H 3 PO 2 . Thus, it has the