Question

According to the kinetic theory of gases:
This question has multiple correct options.
A) Pressure of the gas is due to the collisions of molecules with each other
B) Kinetic energy is proportional to square root of the temperature
C) Pressure of a gas is due to collisions of molecules against the sides of the container
D) There is no force of attraction between gas molecules

Answer 1

Recall the postulates of Kinetic molecular theory of gases. One of the postulates says about the average kinetic energy of the gas molecules. It is assumed in kinetic theory that, average kinetic energy of the gas molecules is directly proportional to the absolute temperature of the gas.

Complete step by step answer:
The theory that attempts to elucidate the behaviour of the gases is known as kinetic molecular theory of gases. Assumptions or postulates of the kinetic molecular theory of gases are:
- A gas consists of a large number of very small spherical tiny particles (identified as molecules) and these molecules are far apart from each other, and are also identical.
- The volume occupied by the molecules is negligible in comparison to the total volume of the gas.
- The gas molecules are in constant random motion. During their motion, they collide with one another and with the side of the container. The pressure of the gas is due to the collisions of molecules with the slides of the container.
- Collisions of the molecules are perfectly elastic, i.e. there is no loss of energy during collisions.
- The laws of classical mechanics, in particular Newton’s second law of motion, are applicable to the molecules in motion.
- There is no force of attraction or repulsion amongst the molecules, i.e. they are moving independent of each other.
- At any instant, average kinetic energy of the gas molecules remains constant for a given temperature, i.e. the average kinetic energy of gas molecules is directly proportional to the absolute temperature of the gas.
So, the correct answer is “Option A,B and D”.

Note: It is seen that on heating a gas at constant volume, the pressure of the gas increases. This is because, on heating, kinetic energy of the gas molecules increases, and thus collisions increases, consequently pressure of the gas increases. Kinetic theory of gases also allows us to derive theoretically all the gas laws, which are: Boyle’s law, Charles’ law, Gay-Lussac’s law, and Avogadro Law.