`dpi-p pi` bond is present in :

Options

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

Answer

To determine which of the given species contains a dπ-pπ bond, we will analyze each option step by step.

### Step 1: Understanding dπ-pπ Bonds
A dπ-pπ bond is a type of pi bond formed by the sidewise overlap of a d orbital from one atom with a p orbital from another atom. This type of bond typically occurs when one of the atoms involved has available d orbitals, which are not present in the second period elements.

### Step 2: Analyzing CO3²⁻ (Carbonate Ion)
- **Elements Involved**: Carbon (C) and Oxygen (O).
- **Valence Shells**: Both carbon and oxygen belong to the second period of the periodic table.
- **D Orbitals**: Neither carbon nor oxygen has d orbitals available in their valence shells.
- **Conclusion**: CO3²⁻ cannot form a dπ-pπ bond.

### Step 3: Analyzing PO4³⁻ (Phosphate Ion)
- **Elements Involved**: Phosphorus (P) and Oxygen (O).
- **Valence Shells**: Phosphorus is in the third period and has d orbitals available, while oxygen is in the second period and does not have d orbitals.
- **Electronic Configuration of Phosphorus**: 1s² 2s² 2p⁶ 3s² 3p³.
- **Bonding in PO4³⁻**: Phosphorus can promote one of its 3s electrons to an empty d orbital to form 5 unpaired electrons, allowing it to form multiple bonds.
- **Bond Formation**: Phosphorus forms 4 sigma bonds (one with each oxygen) and 1 pi bond with one of the oxygen atoms using its d orbital and the p orbital of oxygen.
- **Conclusion**: PO4³⁻ has a dπ-pπ bond.

### Step 4: Analyzing NO3⁻ (Nitrate Ion)
- **Elements Involved**: Nitrogen (N) and Oxygen (O).
- **Valence Shells**: Both nitrogen and oxygen are in the second period.
- **D Orbitals**: Neither nitrogen nor oxygen has d orbitals available.
- **Conclusion**: NO3⁻ cannot form a dπ-pπ bond.

### Step 5: Analyzing NO2⁻ (Nitrite Ion)
- **Elements Involved**: Nitrogen (N) and Oxygen (O).
- **Valence Shells**: Both nitrogen and oxygen are in the second period.
- **D Orbitals**: Neither nitrogen nor oxygen has d orbitals available.
- **Conclusion**: NO2⁻ cannot form a dπ-pπ bond.

### Final Conclusion
From the analysis, only the phosphate ion (PO4³⁻) contains a dπ-pπ bond due to the presence of phosphorus, which has available d orbitals.

### Answer
The species that contains a dπ-pπ bond is **PO4³⁻**.

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