An example of a Lewis acid is

Options

A. NaCl
B. `MgCl_(2)`
C. `AlCl_(3)`
D. `SnCl_(4)`

Explanation

To determine an example of a Lewis acid from the given options (NaCl, MgCl2, AlCl3, and SnCl4), we can analyze each compound based on the definition of a Lewis acid. A Lewis acid is defined as a substance that can accept a pair of electrons to form a covalent bond.

### Step-by-Step Solution:

1. **Understanding Lewis Acids**:
- A Lewis acid is any species that can accept an electron pair. This typically includes metal ions or compounds that have vacant orbitals.

2. **Analyzing the Options**:
- **NaCl**: Sodium chloride is an ionic compound and does not have the ability to accept electron pairs. Therefore, it is not a Lewis acid.
- **MgCl2**: Magnesium chloride is also primarily ionic and does not exhibit the characteristics of a Lewis acid.
- **AlCl3**: Aluminum chloride can act as a Lewis acid because it has a vacant p-orbital that can accept an electron pair. It can form complexes with Lewis bases (like NH3) by accepting their lone pairs.
- **SnCl4**: Tin(IV) chloride also acts as a Lewis acid due to the presence of vacant orbitals that can accept electron pairs.

3. **Conclusion**:
- Both AlCl3 and SnCl4 qualify as Lewis acids. However, since the question asks for an example, we can choose **AlCl3** as a representative example of a Lewis acid.

### Final Answer:
An example of a Lewis acid is **AlCl3**.

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