Question

Find the correct order of \( \text{C} - \text{O} \) bond length among \( \text{CO}, \text{CO}_3^{2-}, \text{CO}_2 \).

• A. \( \text{CO}_2 < \text{CO}_3^{2-} < \text{CO} \)
• B. \( \text{CO} < \text{CO}_3^{2-} < \text{CO}_2 \)
• C. \( \text{CO}_3^{2-} < \text{CO}_2 < \text{CO} \)
• D. \( \text{CO} < \text{CO}_2 < \text{CO}_3^{2-} \)

Hint:

For species with multiple bonds, bond length decreases as bond order increases, and resonance can further affect bond length.

Answer 1

The Correct Option is D

In general, the bond length between carbon and oxygen decreases as the bond order increases. The order of the C–O bond lengths for the given species is: - In \( \text{CO} \), the molecule contains a triple bond between carbon and oxygen, so the bond length is the shortest.
- In \( \text{CO}_2 \), there are two C=O double bonds, which results in a longer bond length than that in CO.
- In \( \text{CO}_3^{2-} \), the C–O bonds are delocalized due to resonance and are weaker and longer than the bonds in \(CO_2\). Thus, the correct order is: \[ \text{CO} < \text{CO}_2 < \text{CO}_3^{2-} \] Therefore, the correct answer is option (D).