Oxygen shows anomalous behaviour due to its :
(A) Small size
(B) Covalency of four
(C) High electronegativity
(D) Tendency to form weak H-bonds
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A) and (C) only
Like the first member of every p-block group, oxygen differs from the rest of its group. The causes are its small size and high electronegativity. Their results include strong hydrogen bonding in \( \ce{H2O} \) (not in \( \ce{H2S} \)), and a covalency limited to four because oxygen has no d orbitals.
(A) Small size — Correct. A cause of the anomalous behaviour.
(B) Covalency of four — Incorrect. This is a result of the absence of d orbitals, not a cause; in practice oxygen rarely exceeds a covalency of two.
(C) High electronegativity — Correct. A cause of the anomalous behaviour.
(D) Tendency to form weak H-bonds — Incorrect. Oxygen forms strong hydrogen bonds (as in water).
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):
Anomalous Behaviour of Oxygen
