Which of the following is an inert gas?

Options

A. `H_(2)`
B. `O_(2)`
C. `N_(2)`
D. Argon

Explanation

To determine which of the following is an inert gas, we can follow these steps:

### Step 1: Understand the Definition of Inert Gases
Inert gases, also known as noble gases, are elements that are non-reactive under standard conditions. They have a complete valence shell, which makes them stable and unlikely to form chemical bonds with other elements.

### Step 2: Identify the Options Given
The options provided are:
- Hydrogen
- Oxygen
- Nitrogen
- Argon

### Step 3: Analyze Each Option
- **Hydrogen (H)**: This is a reactive gas and can form bonds with many elements.
- **Oxygen (O)**: This is also a reactive gas, essential for combustion and respiration.
- **Nitrogen (N)**: While relatively inert at room temperature, it can still react under certain conditions.
- **Argon (Ar)**: This is a noble gas, part of group 18 in the periodic table, and is known for its inertness.

### Step 4: Conclusion
Among the options provided, **Argon (Ar)** is the only inert gas.

### Final Answer
The inert gas from the options given is **Argon (Ar)**.

---