Which of the following can act as ambidentate ligand?
`I^(-),NO_(2)^(-),CN^(-),SCN^(-),C_(2)O_(4)^(2-),NH_(3),en,H_(2)O`

Explanation

To determine which of the given ligands can act as ambidentate ligands, we first need to understand what an ambidentate ligand is. An ambidentate ligand is a type of ligand that has two different donor atoms and can coordinate to a metal ion through either of these donor atoms.

Let's analyze each of the given ligands:

1. **I⁻ (Iodide)**: This is a monodentate ligand, as it has only one donor site (the iodide ion itself). It cannot act as an ambidentate ligand.

2. **NO₂⁻ (Nitrite)**: This ligand can coordinate through either the nitrogen atom or one of the oxygen atoms. Therefore, it can act as an ambidentate ligand.

3. **CN⁻ (Cyanide)**: This ligand has only one donor site (the carbon atom), so it is also a monodentate ligand and cannot act as an ambidentate ligand.

4. **SCN⁻ (Thiocyanate)**: This ligand can coordinate through either the sulfur atom or the nitrogen atom, making it an ambidentate ligand.

5. **C₂O₄²⁻ (Oxalate)**: This ligand has two donor sites (the two oxygen atoms), but it is typically considered a bidentate ligand rather than an ambidentate ligand because it coordinates through both donor sites simultaneously.

6. **NH₃ (Ammonia)**: This ligand has only one donor site (the nitrogen atom) and is a monodentate ligand, so it cannot act as an ambidentate ligand.

7. **en (Ethylenediamine)**: This is a bidentate ligand that coordinates through two nitrogen atoms. It is not ambidentate as it does not have two different types of donor atoms.

8. **H₂O (Water)**: This ligand has only one donor site (the oxygen atom) and is a monodentate ligand, so it cannot act as an ambidentate ligand.

Based on this analysis, the ligands that can act as ambidentate ligands from the given list are:

- **NO₂⁻ (Nitrite)**
- **SCN⁻ (Thiocyanate)**

### Final Answer:
The ambidentate ligands from the given options are **NO₂⁻ and SCN⁻**.