Question

Which one is not an acid salt?

• A. $Na{H}_{2}P{O}_4$
• B. $Na{H}_{2}P{O}_2$
• C. $Na{H}_{2}P{O}_3$
• D. $N{a}_{3}P{O}_3$

Answer 1

Answer: (B)

$Na{H}_{2}P{O}_2$

In case of hydroxides of phosphorus presence of $P—OH/P—O(-)$ bond refers to acidic character.

So in case of $H_{2}P{O}_2^{-}$ there is only 1 $P{O}^{-}$ bond.

Thus it has a basicity = 1.

Since Na(+) also has an acidity of 1 and both H3PO2(conjugate acid) and Na(conjugate base) are strong acid and base respectively, both neutralize each other resulting in a neutral/normal salt.

Hence the correct option is B.