According to VBT the extent of overlapping depends upon types of orbitals involved in overlapping and nature of overlapping. More will be the overlapping and the bond energy will also be high.
Which of the following compound does not form `p pi- p pi` bond ?

Options

A. `SO_(3)`
B. `NO_(3)^(-)`
C. `SO_(4)^(2-)`
D. `CO_(3)^(2-)`

Explanation

To determine which compound does not form a \( p \pi - p \pi \) bond, we need to analyze the bonding characteristics of each compound provided in the options. Let's break down the analysis step by step.

### Step 1: Understand the Concept of \( p \pi - p \pi \) Bonds
- \( p \pi - p \pi \) bonds are formed when two p orbitals from different atoms overlap. This type of bonding is common in compounds where both atoms involved have available p orbitals.

### Step 2: Analyze Each Compound
We will analyze the compounds one by one to see if they can form \( p \pi - p \pi \) bonds.

#### Option 1: \( SO_3 \)
- **Lewis Structure**: Sulfur forms three double bonds with three oxygen atoms.
- **Bonding**: The bonds consist of one sigma bond and one pi bond. The pi bonds involve the p orbitals of sulfur and oxygen.
- **Conclusion**: \( SO_3 \) forms \( p \pi - p \pi \) bonds.

#### Option 2: \( NO_3^- \)
- **Lewis Structure**: Nitrogen is bonded to three oxygen atoms, with one of them having a negative charge.
- **Bonding**: The bonds consist of one sigma bond and two pi bonds. The pi bonds are formed by the overlapping of p orbitals of nitrogen and oxygen.
- **Conclusion**: \( NO_3^- \) forms \( p \pi - p \pi \) bonds.

#### Option 3: \( SO_4^{2-} \)
- **Lewis Structure**: Sulfur is bonded to four oxygen atoms, with some single and some double bonds.
- **Bonding**: The pi bonds are formed by the overlapping of the p orbitals of oxygen and the d orbitals of sulfur.
- **Conclusion**: \( SO_4^{2-} \) does not form \( p \pi - p \pi \) bonds; it forms \( p \pi - d \pi \) bonds.

#### Option 4: \( CO_3^{2-} \)
- **Lewis Structure**: Carbon is bonded to three oxygen atoms, with one of them having a double bond.
- **Bonding**: The bonds consist of one sigma bond and two pi bonds formed by the overlapping of p orbitals of carbon and oxygen.
- **Conclusion**: \( CO_3^{2-} \) forms \( p \pi - p \pi \) bonds.

### Step 3: Final Conclusion
After analyzing all the options:
- The compound that does not form \( p \pi - p \pi \) bonds is **Option 3: \( SO_4^{2-} \)**.