The correct $\mathrm{C}-\mathrm{O}$ bond length among $\mathrm{CO}, \mathrm{CO}_3^{-2}, \mathrm{CO}_2$ is:

• A

  $\mathrm{CO} < \mathrm{CO}_3^{2-} < \mathrm{CO}_2$
• B

  $\mathrm{CO}_3^{2-} < \mathrm{CO}_2 < \mathrm{CO}$
• Correct answer
  C

  $\mathrm{CO} < \mathrm{CO}_2 < \mathrm{CO}_3^{2-}$
• D

  $\mathrm{CO}_2 < \mathrm{CO}_3^{2-} < \mathrm{CO}$

Solution

More is the single bond character more will be the bond length.
Thus, correct order is $\mathrm{CO} < \mathrm{CO}_2 < \mathrm{CO}_3^{--}$ Related Theory Compounds with formal $\mathrm{C} \equiv \mathrm{O}$ triple bonds do not exist except for carbon monoxide, which has a very short, and strong bond (112.8 pm).

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