The number of translational degree of freedom for a diatomic gas is

Options

A. 2
B. 3
C. 5
D. 6

Answer

To determine the number of translational degrees of freedom for a diatomic gas, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Degrees of Freedom**:
- Degrees of freedom refer to the number of independent ways in which a system can move. For gases, this typically includes translational, rotational, and vibrational movements.

2. **Translational Degrees of Freedom**:
- In three-dimensional space, any particle can move in three independent directions: along the x-axis, y-axis, and z-axis. Thus, every molecule, including diatomic molecules, has 3 translational degrees of freedom.

3. **Diatomic Molecule Characteristics**:
- A diatomic molecule consists of two atoms. While the translational degrees of freedom are the same as for a monoatomic gas, diatomic molecules also have additional degrees of freedom due to their structure.

4. **Rotational Degrees of Freedom**:
- Diatomic molecules can rotate around two axes perpendicular to the line joining the two atoms. This gives them 2 rotational degrees of freedom. The rotation around the axis along the bond does not count as it does not change the orientation of the molecule in space.

5. **Total Degrees of Freedom**:
- For a diatomic gas, the total degrees of freedom can be calculated as:
\[ \text{Total Degrees of Freedom} = \text{Translational} + \text{Rotational} + \text{Vibrational} \]
- However, for the question specifically asking about translational degrees of freedom, we focus only on the translational part.

6. **Conclusion**:
- Therefore, the number of translational degrees of freedom for a diatomic gas is **3**.

### Final Answer:
The number of translational degrees of freedom for a diatomic gas is **3**.

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