Question

Which of the following acids is monobasic?

• A. Hypophosphorous acid $\left(H_{3}P{O}_2\right)$
• B. Orthophosphoric acid $\left(H_{3}P{O}_4\right)$
• C. Pyrophosphoric acid $\left(H_4{P}_2{O}_7\right)$
• D. Hypophosphoric acid $\left(H_4{P}_2{O}_6\right)$

Answer 1

Answer: (A)

Hypophosphorous acid $\left(H_{3}P{O}_2\right)$

Hypophosphorous acid $\left(H_{3}P{O}_2\right)$ has one replaceable hydrogen. The hydrogen attached to $P$ does not contribute to the acidity in acids.