Bidentate ligand out of the following is :

Options

A. EDTA
B. Ethylenediamine
C. Acetate
D. Pyridine

Explanation

To determine which of the given options is a bidentate ligand, we need to understand the definition of a bidentate ligand and analyze each option accordingly.

### Step-by-Step Solution:

1. **Definition of Bidentate Ligand**:
A bidentate ligand is a type of ligand that has two donor atoms capable of coordinating to a central metal atom or ion. This means it can form two bonds with the metal.

2. **Analyzing the Options**:
- **Ethylenediamine (en)**: This compound has the structure NH2-CH2-CH2-NH2. The two nitrogen atoms (NH2 groups) can donate a pair of electrons each, making it a bidentate ligand.
- **Tetraacetate**: This ligand typically refers to the acetate ion (CH3COO-), which has only one donor atom per acetate group. Therefore, it is a monodentate ligand.
- **EDTA**: Ethylenediaminetetraacetic acid is a hexa-dentate ligand, as it has six donor atoms (four carboxylate groups and two amine groups).
- **Pyridine**: This compound has a nitrogen atom in a six-membered ring and can donate only one pair of electrons, making it a monodentate ligand.

3. **Conclusion**:
Based on the analysis, the only ligand from the options that qualifies as a bidentate ligand is **Ethylenediamine (en)**.

### Final Answer:
The bidentate ligand out of the given options is **Ethylenediamine**.

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