The order of bond length is

• Correct answer
  A

  \(\mathrm{O}_2 < \mathrm{O}_3 < \mathrm{O}_2{ }^{2-}\)
• B

  \(\mathrm{O}_2 < \mathrm{O}_2{ }^{2-} < \mathrm{O}_3\)
• C

  \(\mathrm{O}_2{ }^{2-} < \mathrm{O}_3 < \mathrm{O}_2\)
• D

  \(\mathrm{O}_2=\mathrm{O}_2{ }^{2-} > \mathrm{O}_3\).

Solution

Ozone molecule is V-shaped with \(\mathrm{O}-\mathrm{O}\) bond length \(1.278 Å\).
The bond length is intermediate between that for a single bond \(\left(1.48 Å\right.\) as in \(\left.\mathrm{H}_2 \mathrm{O}_2\right)\) and for a double bond (1.21 \(Å\) as in \(\mathrm{O}_2\)).

Hence, the correct answer is option: 'A'.