Find the number of ligand (s) which is//are polydentate ligand
`en, dmg dien `EDTA` .

Explanation

To determine the number of polydentate ligands from the given set (en, dmg, dien, EDTA), we will analyze each ligand one by one to identify their donor atoms and how many sites they have for coordination.

### Step-by-Step Solution:

1. **Identify Ethylenediamine (en)**:
- Ethylenediamine has the formula NH₂CH₂CH₂NH₂.
- It contains two nitrogen atoms that can donate lone pairs.
- **Conclusion**: Ethylenediamine is a bidentate ligand (2 donor atoms).

2. **Identify Dimethylglyoxime (dmg)**:
- Dimethylglyoxime has the structure CH₃C(=N-OH)C(=N-OH)CH₃.
- It has two nitrogen atoms that can coordinate to a metal center.
- **Conclusion**: Dimethylglyoxime is also a bidentate ligand (2 donor atoms).

3. **Identify Diethylenetriamine (dien)**:
- Diethylenetriamine has the formula NH₂CH₂CH₂NHCH₂CH₂NH₂.
- It contains three nitrogen atoms that can donate lone pairs.
- **Conclusion**: Diethylenetriamine is a tridentate ligand (3 donor atoms).

4. **Identify Ethylenediaminetetraacetic acid (EDTA)**:
- EDTA has the structure CH₂(COOH)₂N(CH₂COOH)₂.
- It contains four carboxylate (COO⁻) groups and two nitrogen atoms.
- This gives a total of six donor atoms (4 oxygen and 2 nitrogen).
- **Conclusion**: EDTA is a hexadentate ligand (6 donor atoms).

### Summary of Findings:
- **en**: Bidentate (2 donor atoms)
- **dmg**: Bidentate (2 donor atoms)
- **dien**: Tridentate (3 donor atoms)
- **EDTA**: Hexadentate (6 donor atoms)

### Final Answer:
The polydentate ligands from the given list are:
- **dien** (tridentate)
- **EDTA** (hexadentate)

Thus, the number of polydentate ligands is **2**.

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