Question

# According to the Kinetic theory of gases there are:A. Intermolecular forcesB. Molecules which have considerable volumeC. No intermolecular forces of attractionD. The velocity of molecules decreases for each collision.

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Hint:According to the postulates of the Kinetic theory of gases, molecules of a gas are point masses and are identical for the same gas. Therefore, the volume and the size of the gas are negligible.

Also, the momentum of the molecules is conserved. Thus, the velocity remains the same.

Complete step by step solution:
In Kinetic theory of gases, molecules of each gas are identical but different from that of other gases. In actual gases or real gases, there are intermolecular forces. But since the kinetic theory is only applicable for ideal gases, there are no intermolecular forces.

Hence, option (A) is not the correct answer.

Molecules of a gas are point masses. They are rigid and perfectly elastic spheres. The volume of molecules is negligible as compared to the volume of the gas sample. Therefore, the gas molecules do not have a considerable volume.

Hence, option (B) is not the correct answer.

One of the postulates is that the molecules are rigid and perfectly elastic spheres. This means that momentum and Kinetic energy are conserved. The momentum is conserved that means the velocity does not change after the collision.

Since, momentum = $m\upsilon$

where, ‘m’ and ‘$\upsilon$’ are mass and velocities of the molecules respectively.

Thus, option (D) is not correct, as the velocity remains the same for each collision.

Hence, option (C) is the correct answer as there are no intermolecular forces of attraction.

Note:The Kinetic theory of gases is applicable for ideal gases and not for real gases. In this theory of ideal gases, the factors like the intermolecular forces and gravitational attraction are neglected.

The momentum is conserved, provided physical conditions such as pressure and temperature do not change. Increasing the temperature will increase the velocity of molecules and thus the momentum will increase.