Which of the following postulates of kinetic theory of gases is not correct ?

Options

A. Gases consist of particles which are in continuous , random motion .
B. The particles are infinitely small and very close to each other.
C. The collisions of the particles with each other are elastic .
D. The pressure of a gas is caused by the collisions of gas particles with the wall of the container .

Explanation

To determine which postulate of the kinetic theory of gases is not correct, we will analyze each of the given statements one by one.

### Step 1: Analyze the first statement
**Statement 1:** Gases consist of particles which are in continuous and random motion.

- This statement is correct. According to the kinetic theory of gases, gas particles are always in motion, and their movement is random.

**Hint:** Remember that gas particles are always moving and do not have a fixed position.

### Step 2: Analyze the second statement
**Statement 2:** The particles are infinitely small and very close to each other.

- This statement is partially correct. While it is true that gas particles are considered to be infinitely small, they are not close to each other. In fact, gas particles are far apart due to minimal intermolecular forces.

**Hint:** Think about the spacing between gas particles compared to solids and liquids.

### Step 3: Analyze the third statement
**Statement 3:** The collisions of the particles with each other are elastic.

- This statement is correct. In the kinetic theory, collisions between gas particles are elastic, meaning that there is no loss of kinetic energy during these collisions.

**Hint:** Elastic collisions mean that total kinetic energy is conserved.

### Step 4: Analyze the fourth statement
**Statement 4:** The pressure of a gas is caused by collisions of gas particles with the wall of the container.

- This statement is also correct. The pressure exerted by a gas is a result of gas particles colliding with the walls of their container.

**Hint:** Consider how gas pressure is related to particle collisions with surfaces.

### Conclusion
After analyzing all the statements, we find that the second statement is the one that is not correct. The correct interpretation is that while gas particles are infinitely small, they are not close to each other; they are actually far apart.

**Final Answer:** The incorrect postulate is: "The particles are infinitely small and very close to each other."