Question

Which of the following is a true statement for the acids of phosphorus: $H_{3}P{O}_2,H_{3}P{O}_3$ and $H_{3}P{O}_4$?

• A. The order of their acidic strength is $H_{3}P{O}_4>H_{3}P{O}_3>H_{3}P{O}_2$.
• B. All of them are reducing in nature.
• C. All of them are tribasic acids.
• D. The geometry of phosphorus is tetrahedral in all the three.

Answer 1

The correct option is D The geometry of phosphorus is tetrahedral in all the three.

The option (D) represents the true statement.
The geometry of phosphorus is tetrahedral in all the three oxyacids. P atom is $s{p}^3$ hybridised.
(A) In the given oxyacids of phosphorous, the number of unprotonated oxygen, responsible for the enhancement of acidity due to inductive effect, remains the same with the result dissociation constant also remains nearly same. Hence, the acid strength doe not vary much with the oxidation number of P atom.

(B) $H_{3}P{O}_4$ is non reducing as it lacks $P-H$ group. $H_{3}P{O}_3$ and $H_{3}P{O}_2$ are reducing in nature as they contain $P-H$ bond.

(C) $H_{3}P{O}_4$ is tribasic, $H_{3}P{O}_3$ is dibasic and $H_{3}P{O}_2$ is monobasic.