`d pi = p pi` bond present in:

Options

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

Answer

To determine which of the given ions contains a dπ-pπ bond, we need to analyze the electronic configuration and bonding characteristics of each option provided.

### Step-by-Step Solution:

1. **Identify the Central Atom and Its Electron Configuration:**
- **Carbonate Ion (CO₃²⁻):**
- Central atom: Carbon (C)
- Ground state: 1s² 2s² 2p²
- Excited state: 1s² 2s¹ 2p³
- Forms p-π bonds with oxygen.

- **Phosphate Ion (PO₄³⁻):**
- Central atom: Phosphorus (P)
- Ground state: 1s² 2s² 2p⁶ 3s² 3p³
- Excited state: 1s² 2s² 2p⁶ 3s² 3p³ 3d¹ (involves 3d orbitals)
- Forms d-π bonds with oxygen.

- **Nitrate Ion (NO₃⁻):**
- Central atom: Nitrogen (N)
- Ground state: 1s² 2s² 2p³
- Excited state: 1s² 2s² 2p³ (does not involve d orbitals)
- Forms p-π bonds with oxygen.

- **Nitrite Ion (NO₂⁻):**
- Central atom: Nitrogen (N)
- Ground state: 1s² 2s² 2p³
- Excited state: 1s² 2s² 2p³ (does not involve d orbitals)
- Forms p-π bonds with oxygen.

2. **Determine the Type of Bonds Formed:**
- In the **carbonate ion**, only p-π bonds are formed between carbon and oxygen.
- In the **phosphate ion**, d-π-p-π bonds can be formed due to the presence of 3d orbitals in phosphorus and unpaired p electrons in oxygen.
- In the **nitrate ion**, only p-π bonds are formed.
- In the **nitrite ion**, only p-π bonds are formed.

3. **Conclusion:**
- The only ion that can form a d-π-p-π bond is the **phosphate ion (PO₄³⁻)** due to the presence of the 3d subshell in phosphorus.

### Final Answer:
The dπ-pπ bond is present in the **phosphate ion (PO₄³⁻)**.