Question

Explain, on the basis of kinetic theory, how the pressure of gas changes if its volume is reduced at constant temperature. 

Answer 1

The average kinetic energy per molecule of a gas is constant at constant temperature. When the volume of a gas is reduced at constant temperature, the number of collisions of gas molecules per unit time with the walls of the container increases. This increases the momentum transferred per unit time per unit area, i.e. the force exerted by the gas on the walls. Hence, the pressure of the gas increases.