Question

Phosphorus has the oxidation state of + 3 in

• A. Phosphorous acid
• B. Orthophosphoric acid
• C. Hypophosphorous acid
• D. Metaphosphoric acid

Answer 1

Answer: (A)

Phosphorous acid

Answer 2

O.N. of P in ${H_3PO_3}$ (phosphorous acid) 3 $\times$ 1 + x + 3 $\times$ (- 2) = 0 or x = + 3
In orthophosphoric acid ${(H3PO4)}$ O.N. of P is + 5, in hypophosphorous acid ${(H3PO2)}$ it is + 1 while in metaphosphoric acid ${(HPO3)}$, it is + 5.