Question

In which of the following oxidation state of phosphorous is +3?

• A. Orthophosphoric acid
• B. Pyrophosphoric acid
• C. Orthophosphorous acid
• D. Metaphosphoric acid

Answer 1

Answer: (C)

Orthophosphorous acid

Answer 2

Orthophosphoric acid $H_{3}P^{+5}O_{4}$
Pyrophosphoric acid $H_{4}P^{+5}_{2}O_{7}$
Orthophosphorous acid $H_{3}P^{+3}O_{3}$
Metaphosphoric acid $HP^{+5}O_{3}$
Thus, orthophosphoric acid has +3 oxidation state