Gas Laws

To solve the problem, we need to identify which of the following is not an inert gas element.

1. Inert Gases (Noble Gases):
Inert gases, also known as noble gases, are the elements in Group 18 of the periodic table. They are characterized by having full electron shells, making them stable and non-reactive. The inert gases include:

• Helium (He)
• Neon (Ne)
• Argon (Ar)

2. Analyzing the Options:
- Helium (He), Neon (Ne), and Argon (Ar) are all inert gases.
- Sodium (Na) is an alkali metal and is highly reactive, not an inert gas.

Final Answer:
The element that is not an inert gas is Sodium (Na) (Option B).