Question

The correct order of increasing $C - O$ bond length $CO, CO^{2-}_3 , CO_2$ is:

• A. $CO < CO_2 < CO^{2-}_3$
• B. $CO_2 < CO^{2-}_3 < CO $
• C. $CO < CO^{2-}_3 < CO_2 $
• D. $ CO^{2-}_3 < CO_3 < CO $

Answer 1

Answer: (A)

The bond order of $CO$ is $3$ .
The bond order of $CO _{2}$ is $2$ .
The bond order of $CO _{3}^{2-}$ is $1.33$ (due to resonance).
Since, bond length $\propto \frac{1}{\text { bond order }}$
So, bond length order is $CO < CO _{2}< CO _{3}^{2-}$.