Question

Hypo-phosphorus acid, $H_{3}P{O}_2$ is

• A. a monobasic acid
• B. atribasicacid
• C. a dibasic acid
• D. not acidic at all

Answer 1

Answer: (A)

Hypophosphorus acid $H_{3}P{O}_2$ is a monobasic acid because it forms only one type of salts eq. sodium hydrogen phosphite $\left(Na{H}_{2}P{O}_2\right)$
$NaOH+H_{3}P{O}_2⟶Na{H}_{2}P{O}_2+H_{2}O$
The structure of $H_{3}P{O}_2$ is following

In the structure of hypophosphorus acid two hydrogen atom is attached to phosphorus (These two hydrogen atoms are non-ionisable) and one hydrogen atom is attached to oxygen atom and this hydrogen atom is ionisable. Therefore, hypophosphorus acid forms only one type of salt and due to presence of only one ionisable hydrogen atom it is a monobasic acid.
$H_{3}P{O}_2\rightleftharpoons H_{2}P{O}_2^{-}+H^{+}$