Incorrect postulate of kinetic theory of gases:

Options

A. Gas particles move in random motion
B. Forces between gas molecules are negligible
C. Gas molecules with higher molar mass have more kineticn energy
D. Collision between gas molecules are elastic

Answer

To determine the incorrect postulate of the kinetic theory of gases, let's first outline the main postulates of the theory:

### Step 1: Identify the Postulates of Kinetic Theory of Gases
1. **Gas Molecules are Small and Far Apart**: The molecules of a gas are considered to be point particles that are far apart from each other, meaning that most of the volume of the gas is empty space.

2. **Random Motion**: Gas molecules are in constant random motion, moving in all directions.

3. **Collisions**: Gas molecules collide with each other and with the walls of their container. These collisions are the source of gas pressure.

4. **Elastic Collisions**: When gas molecules collide, they do not lose kinetic energy; the collisions are perfectly elastic.

5. **No Intermolecular Forces**: There are no attractive or repulsive forces between gas molecules; they do not exert forces on one another.

### Step 2: Analyze the Options
Now, let's analyze the provided options to find the incorrect postulate:
- **Gas moving in random motions**: This is a correct postulate.
- **The force between the gas molecules is negligible**: This is also a correct postulate.
- **Gas molecules with higher molar mass have more kinetic energy**: This is incorrect. Kinetic energy is dependent on temperature, not molar mass.
- **Collision between the gas molecules is perfectly elastic**: This is a correct postulate.

### Step 3: Conclusion
The incorrect postulate of the kinetic theory of gases is that "gas molecules with higher molar mass have more kinetic energy." This statement is misleading because the average kinetic energy of gas molecules is directly proportional to the temperature of the gas, not their molar mass.

### Final Answer
The incorrect postulate of the kinetic theory of gases is: **Gas molecules with higher molar mass have more kinetic energy.**

---