The correct statement(s) about \(O_3\) is (are)

1. \(O-O\) bond length are equal
2. Thermal decomposition of \(O_3\) is endothermic
3. \(O_3\) is diamagnetic in nature
4. \(O_3\) has bent structure

Choose the correct answer from the options given below:

A, C, D

The correct answer is option 1. A, C, D

A. O−O bond lengths are equal:

This is true.  The O-O bond lengths in ozone (O₃) are equivalent. Ozone has a bent molecular geometry with a resonance structure, where the bonding is delocalized between the two oxygen-oxygen bonds. This delocalization of electrons leads to an average bond length that is intermediate between a single bond and a double bond, resulting in both O-O bonds being of equal length in the molecule. This resonance effect makes the O-O bonds in O₃ identical in length.

B. Thermal decomposition of O₃ is endothermic:

This is true. The thermal decomposition of ozone (\(O_3\)) is endothermic. The reaction for the decomposition of ozone is:

\(2 O_3 \rightarrow 3 O_2\)

This reaction requires an input of energy because the bond energy of the O-O bonds in ozone is higher than in the oxygen molecules (\(O_2\)), making it necessary to absorb heat to break the O-O bonds in ozone. As a result, the decomposition process absorbs energy from the surroundings, making it endothermic.

C. O₃ is diamagnetic in nature:

This is false. Ozone (\(O_3\)) is paramagnetic in nature, not diamagnetic. This is because it has an odd number of electrons, specifically 24 valence electrons (8 from each oxygen atom). According to molecular orbital theory, the unpaired electrons in the \(\pi^*\) anti-bonding orbitals make ozone paramagnetic.

Diamagnetic substances, on the other hand, have all their electrons paired and are repelled by a magnetic field, which is not the case with ozone. Therefore, \(O_3\) exhibits paramagnetism.

D. O₃ has a bent structure:

Ozone (\(O_3\)) has a bent structure. The molecule adopts a bent shape due to the repulsion between the lone pairs of electrons on the central oxygen atom.

The central oxygen in ozone forms two sigma bonds with the other oxygen atoms and also has a lone pair of electrons. The bond angle between the oxygen atoms in ozone is approximately 117°, which is less than the ideal 120° of a trigonal planar geometry due to the lone pair-bond pair repulsion being stronger than bond-bond repulsion.

This bent structure is a result of the resonance between two major contributing structures, which causes delocalization of the electrons, leading to equivalent O-O bond lengths.

Thus, the correct statements are A,C, and D.