Here's how to determine the number of occupied sublevels in a chlorine atom's ground state:

1. Electronic Configuration of Chlorine:

* Chlorine has an atomic number of 17, meaning it has 17 electrons.

* Its electronic configuration is: 1s² 2s² 2p⁶ 3s² 3p⁵

2. Identifying Sublevels:

* Sublevels are denoted by the letters s, p, d, and f.

* The number in front of the letters (e.g., 2s, 3p) indicates the principal energy level.

3. Counting Occupied Sublevels:

* 1s: Occupied

* 2s: Occupied

* 2p: Occupied

* 3s: Occupied

* 3p: Occupied

Therefore, there are a total of 5 occupied sublevels in a chlorine atom's ground state.