The correct statement(s) about \(O_3\) is (are)
- \(O-O\) bond length are equal
- Thermal decomposition of \(O_3\) is endothermic
- \(O_3\) is diamagnetic in nature
- \(O_3\) has bent structure
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, C, D
A. O–O bond lengths are equal — True. Ozone is a resonance hybrid of two structures, so both O–O bonds are identical (128 pm), in between a single and a double bond.
B. Thermal decomposition of O3 is endothermic — False. Ozone is thermodynamically unstable with respect to oxygen; its decomposition \( \ce{2O3 -> 3O2} \) releases heat (it is exothermic, ΔH negative) and is accompanied by an increase in entropy.
C. O3 is diamagnetic in nature — True. All electrons in ozone are paired.
D. O3 has a bent structure — True. The central oxygen carries a lone pair, so the molecule is angular, with a bond angle of about 117°.
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):
Properties – “… Ozone is thermodynamically unstable with respect to oxygen since its decomposition into oxygen results in the liberation of heat (ΔH is negative) and an increase in entropy (ΔS is positive). These two effects reinforce each other, resulting in large negative Gibbs energy change (ΔG) for its conversion into oxygen. … The two oxygen-oxygen bond lengths in the ozone molecule are identical (128 pm) and the molecule is angular as expected with a bond angle of about 117°.”