Calculate the total number of degree of freedom for a mole of diatomic gas at STP.

Options

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

Explanation

To calculate the total number of degrees of freedom for a mole of diatomic gas at standard temperature and pressure (STP), we can follow these steps:

### Step 1: Understand the Degrees of Freedom
A diatomic gas consists of two atoms. The degrees of freedom refer to the number of independent ways in which the molecules can move or store energy.

### Step 2: Translational Degrees of Freedom
For any gas, there are three translational degrees of freedom. These correspond to movement along the three spatial dimensions (x, y, and z axes).

- **Translational Degrees of Freedom = 3**

### Step 3: Rotational Degrees of Freedom
Diatomic molecules can also rotate. They have two rotational degrees of freedom because they can rotate about two axes perpendicular to the line joining the two atoms. The rotation about the axis along the bond does not count as a degree of freedom because it does not change the orientation of the molecule in space.

- **Rotational Degrees of Freedom = 2**

### Step 4: Total Degrees of Freedom
Now, we can sum the translational and rotational degrees of freedom to find the total degrees of freedom for a diatomic gas.

\[ \text{Total Degrees of Freedom} = \text{Translational Degrees of Freedom} + \text{Rotational Degrees of Freedom} \]

\[ \text{Total Degrees of Freedom} = 3 + 2 = 5 \]

### Step 5: Conclusion
Thus, the total number of degrees of freedom for a mole of diatomic gas at STP is **5**.