According to the kinetic theory of gases, at absolute temperature

Options

A. water freezes
B. liquid helium freezes
C. molecular motion stops
D. liquid hydrogen freezes

Answer

To solve the question regarding the kinetic theory of gases at absolute temperature, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Kinetic Theory of Gases**:
- According to the kinetic theory of gases, the temperature of a gas is related to the average kinetic energy of its molecules.

2. **Mean Kinetic Energy Relation**:
- The mean kinetic energy (KE) of a gas molecule is given by the formula:
\[ KE = \frac{1}{2} mv^2 \]
where \( m \) is the mass of the gas molecule and \( v \) is its average velocity.

3. **Direct Proportionality to Absolute Temperature**:
- The kinetic theory states that the mean kinetic energy of gas molecules is directly proportional to the absolute temperature (T):
\[ KE \propto T \]
- This implies that as the temperature increases, the average kinetic energy of the molecules also increases.

4. **Expression for Mean Kinetic Energy**:
- We can express this relationship mathematically as:
\[ KE = kT \]
where \( k \) is a proportionality constant.

5. **Behavior at Absolute Zero (0 Kelvin)**:
- At absolute zero (0 Kelvin), the temperature is such that:
\[ T = 0 \text{ K} \]
- Substituting this into the equation for kinetic energy gives:
\[ KE = k \cdot 0 = 0 \]
- This indicates that the mean kinetic energy of the gas molecules is zero.

6. **Conclusion about Molecular Motion**:
- Since the kinetic energy is zero at absolute zero, it implies that all molecular motion stops. Therefore, absolute zero is defined as the temperature at which all molecular motion ceases.

### Final Answer:
At absolute temperature (0 Kelvin), the mean kinetic energy of gas molecules is zero, indicating that all molecular motion stops.