Question

Which of the following statements are correct about \(\mathrm{CO_3^{2-}}\) ion?

1. The hybridisation of the central atom is \(sp^2\).
2. The average formal charge on each oxygen atom is \(-\frac{2}{3}\).
3. The resonance hybrid structure does not have one C--O single bond and two C=O double bonds; all C--O bonds are equivalent.
4. All C--O bond lengths are equal.

• A. II \& IV only
• B. I \& II only
• C. II \& III only
• D. I \& III only \bigskip

Hint:

For the carbonate ion \(\mathrm{CO_3^{2-}}\):

• Central atom is \(sp^2\)-hybridised.
• Geometry is trigonal planar.
• All three C--O bonds are equivalent due to resonance.
• Bond order of each C--O bond is \(\dfrac{4}{3}\).

Answer 1

The Correct Option is A

Step 1: I: CO₃²⁻ C is sp² → correct. II: -2 charge delocalized over 3 O, average 0.67 → correct. III: Resonance hybrid has three equal bonds, not one single and two double → incorrect. IV: All C-O bonds equal length → correct. II & IV only.

Step 2: Write the final answer. \(\boxed{\text{II \& IV only}.}\)