Question

Which of the assumptions of the kinetic-molecular theory best explains the observations that a gas can be compressed?

• A. Gas molecules move at random motion with no attractive forces between them
• B. The velocity of gas molecules is proportional to their Kelvin temperature
• C. The amount of space occupied by a gas is much greater than the space occupied by the actual gas molecules
• D. In collisions with the walls on the walls of the container or with other molecules, energy is conserved

Answer 1

The correct option is C

The amount of space occupied by a gas is much greater than the space occupied by the actual gas molecules

Explanation of correct answer:

(c) The velocity of gas molecules is directly proportional to their kelvin temperature so the amount of space occupied by a gas is much more than the space occupied by the actual gas molecules because the collisions with the walls of the container or with other molecules are elastic.

Explanation of incorrect answer:

(A)

• Gas particles are in constant rapid motion in random directions and the Collisions between gas particles and the container walls are elastic collisions.
• There are no forces of attraction or repulsion between gas particles.

(B) According to Charles law, at constant pressure, the volume V of a gas is directly proportional to its absolute (Kelvin) temperature T, or V/T = k.

(D)

• Gas particles are in constant rapid motion in random directions and the Collisions between gas particles and between particles and the container walls are elastic collisions.
• They change their directions and kinetic energies, but the total kinetic energy is conserved.

Hence, C is the correct option.