Question

Which among the following oxoacids of phosphorus shows a tendency of disproportionation?

• A. Phosphinic aicd $\left(H_{3}P{O}_2\right)$
• B. Orthophosphoric acid $\left(H_{3}P{O}_4\right)$
• C. Phosphonic acid $\left(H_{3}P{O}_3\right)$
• D. Pyrophosphoric acid $\left(H_4{P}_2{O}_7\right)$

Answer 1

Answer: (C)

Phosphonic acid $\left(H_{3}P{O}_3\right)$

Phosphonic acid $\left(H_{3}P{O}_3\right)$ shows a tendency of disproportionation.
When phosphonic acid is heated, it dissociates to give phosphoric acid and phosphine.
$4H_{3}P{O}_3\to 3H_{3}P{O}_4+P{H}_3$