The C-O bond length in $\mathrm{CO}, \mathrm{CO}_{2}$ and $\mathrm{CO}_{3}{ }^{2-}$ follows the order -

• Correct answer
  A

  $\mathrm{CO} < \mathrm{CO}_{2} < \mathrm{CO}_{3}{ }^{2-}$
• B

  $\mathrm{CO}_{2} < \mathrm{CO}_{3}{ }^{2-} < \mathrm{CO}$
• C

  $\mathrm{CO}>\mathrm{CO}_{2}>\mathrm{CO}_{3}^{2-}$
• D

  $\mathrm{CO}_{3}{ }^{2-} < \mathrm{CO}_{2} < \mathrm{CO}$

Solution

Bond Length $\propto \frac{1}{\text { Bond Order }}$ $\mathrm{CO}, \mathrm{B} . \mathrm{O} .=3$ $\mathrm{O}=\mathrm{C}=\mathrm{O}, \mathrm{B} . \mathrm{O} .=2$

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