Question

The true statement for the acids of phosphorus, $H_3PO_2$, $H_3PO_3$ and $H_3PO_4$ is

• A. the order of their acidity is $H_3PO_4 > H_3PO_3 > H_3PO_2$
• 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

Answer: (D)

the geometry of phosphorus is tetrahedral in all the three

Answer 2

$H_3PO_2, H_3PO_3$ and $H_3PO_4$ contain one, two and three ionisable hydrogen atoms respectively. ${H3PO2 <=> H+ + H2PO2^-}$ ${H3PO3 <=> H+ + H2PO3^-}$ ${ <=> H+ + HPO3^{2-}}$ ${H3PO4 <=> H+ + H2PO4^-}$ ${ <=> H+ + HPO4^{2-}}$ ${ <=> H+ + PO4^{3-}}$ But there is very little difference in acidity. As P is $sp^3$ hybridised in all therefore all are tetrahedral.