What is the IUPAC name of C{{H}_{3}}COCl?

The given compound is **C\(_{3}\)COCl**, which is **acetyl chloride**. Let's break it down for the IUPAC naming:

### Steps to determine the IUPAC name:
1. **Identify the parent chain:**
The structure is a derivative of ethane, with two carbon atoms. The main chain is "ethan" (as it contains two carbon atoms).

2. **Identify the functional group:**
The compound contains an acyl chloride group (-COCl). In IUPAC nomenclature, when the functional group is -COCl, it is named as "carbonyl chloride" (or "oyl chloride") attached to the parent chain.

3. **Apply IUPAC rules:**
The base alkane name for two carbons is **ethane**. The suffix for an acyl chloride group (-COCl) is **oyl chloride**.

Thus, the IUPAC name of C\(_3\)COCl is **ethanoyl chloride**.

### Common name:
The common name of this compound is **acetyl chloride**.

### Summary:
- IUPAC name: **Ethanoyl chloride**
- Common name: **Acetyl chloride**