The correct order of increasing C - O bond length `CO, CO_3^(2-) , CO_2` is :

Options

A. `CO lt CO_2 lt CO_3^(2-)`
B. `CO_2 lt CO_3^(2-) lt CO`
C. `CO lt CO_3^(2-) lt CO_2`
D. `CO_3^(2-) lt CO_3 lt CO`

Answer

To determine the correct order of increasing C - O bond length for CO, CO₂, and CO₃²⁻, we need to analyze the bonding characteristics of each molecule.

### Step-by-Step Solution:

1. **Identify the Bonding in Each Compound:**
- **CO (Carbon Monoxide):** In CO, there is a triple bond between carbon and oxygen. This triple bond consists of one sigma bond and two pi bonds.
- **CO₂ (Carbon Dioxide):** In CO₂, there are two double bonds (one with each oxygen atom). Each double bond consists of one sigma bond and one pi bond.
- **CO₃²⁻ (Carbonate Ion):** In CO₃²⁻, there are three resonance structures. Each bond between carbon and oxygen has a partial double bond character due to resonance, but on average, it can be considered as having one double bond and two single bonds.

2. **Determine the Hybridization:**
- **CO:** The carbon in CO is sp hybridized due to the triple bond.
- **CO₂:** The carbon in CO₂ is sp² hybridized due to the double bonds.
- **CO₃²⁻:** The carbon in CO₃²⁻ is sp² hybridized as well, but the bonds are partially double due to resonance.

3. **Analyze Bond Lengths:**
- **Triple Bonds (CO):** Generally, triple bonds are shorter than double bonds due to greater overlap of orbitals. Therefore, CO will have the shortest bond length.
- **Double Bonds (CO₂):** CO₂ has a permanent double bond, which is shorter than the average bond length in CO₃²⁻.
- **Resonance (CO₃²⁻):** The bonds in CO₃²⁻ are longer than the double bond in CO₂ because they have partial double bond character, making them longer than a true double bond.

4. **Order of Increasing Bond Length:**
- From the analysis, we can conclude that the order of increasing C - O bond length is:
- CO (shortest)
- CO₂ (shorter than CO₃²⁻)
- CO₃²⁻ (longest)

### Final Order:
Thus, the correct order of increasing C - O bond length is:
**CO < CO₂ < CO₃²⁻**