The degrees of freedom of a triatomic gas is

Options

A. 2
B. 4
C. 6
D. 8

Answer

To determine the degrees of freedom of a triatomic gas, we need to consider both translational and rotational motions. Let's break it down step by step.

### Step 1: Understanding Degrees of Freedom
Degrees of freedom refer to the number of independent ways in which a system can move. For a gas, these movements can be translational (movement in space) and rotational (spinning around an axis).

### Step 2: Translational Degrees of Freedom
For any gas molecule, translational motion occurs in three dimensions (x, y, and z). Therefore, for a triatomic gas, the translational degrees of freedom are:
- 3 (one for each dimension).

### Step 3: Rotational Degrees of Freedom
The rotational degrees of freedom depend on the shape of the molecule:
- **Linear Triatomic Gas**: For a linear molecule, it can rotate about two axes perpendicular to the molecular axis. Therefore, the rotational degrees of freedom are:
- 2 (rotations about two perpendicular axes).

- **Non-linear Triatomic Gas**: If the triatomic gas is non-linear, it can rotate about three axes. However, for this question, we will focus on the linear case.

### Step 4: Total Degrees of Freedom
Now, we can sum the translational and rotational degrees of freedom:
- Translational degrees of freedom = 3
- Rotational degrees of freedom (for linear triatomic gas) = 2

Total degrees of freedom = Translational + Rotational = 3 + 2 = 5

### Conclusion
Thus, the degrees of freedom of a linear triatomic gas is **5**.