Answer: Option (b) is the correct answer.
Explanation:
In liquids, the molecules are held by strong intermolecular forces of attraction as compared to gases. Due to which they are able to collide and slide past each other. Hence, they have a medium kinetic energy.
And, in liquid molecules there is moderate intermolecular distance between the particles.
In gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move very rapidly from one place to another leading to more number of collisions.
Hence, gases are able to expand more rapidly as compared to liquids. Therefore, between the atoms of a gas there are large intermolecular distances.
Therefore, we can conclude that the statement particles collide in gas so Substance X is a gas, best describes the two substances.
