The number of ionisable hydrogens present in the product obtained from a reaction of phosphorus trichloride and phosphonic acid is:
- (A)1
- (B)3
- (C)0
- (D)2✓ Correct
Answer: (D)
Solution
Phosphonic acid is H₃PO₃ (or better written as HPO(OH)₂). When PCl₃ reacts with H₃PO₃, it forms pyrophosphonic acid H₄P₂O₅. This compound has 2 ionizable hydrogens (the two P-OH groups). The P-H hydrogens are not acidic/ionizable. Therefore, the answer is 2.
JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Single correct option