Match List I with List II
|
List I (Oxoacids of phosphorus) |
List II (Characteristic Bonds) |
| (A) \(H_3PO_2\) | (I) 7 |
| (B) \(H_4P_2O_5\) | (II) 12 |
| (C) \(H_4P_2O_6\) | (III) 4 |
| (D) \((HPO_3)_3\) | (IV) 6 |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-III, B-IV, C-I, D-II
Count the characteristic bonds in each structure:
(A) H3PO2 (hypophosphorous acid): one P–OH, two P–H, one P=O → 1 + 2 + 1 = 4 → (III)
(B) H4P2O5 (pyrophosphorous acid): two P–OH, two P–H, two P=O → 2 + 2 + 2 = 6 → (IV)
(C) H4P2O6 (hypophosphoric acid): four P–OH, two P=O, one P–P → 4 + 2 + 1 = 7 → (I)
(D) (HPO3)3 (cyclotrimetaphosphoric acid): three P–OH, three P=O and three P–O–P bridges. Each bridge is made of two P–O bonds, so the six-membered ring has six P–O bonds → 3 + 3 + 6 = 12 → (II)
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Oxoacids of Phosphorus – …
