Explanation:
In gases, the molecules are held together by weak Vander waal forces. Due to this they have more kinetic energy and hence, more number of collisions take place between the molecules of a gas.
Therefore, they tend to diffuse at a faster rate and distance traveled by them is more as compared to the distance traveled by the molecules of a liquid.
On the other hand in liquids, the molecules are held by more strong intermolecular forces of attraction as compared to gases but not strong enough as they are in solids. Due to this molecules of a liquid are able to slide past each other. Hence, they have medium kinetic energy.
Therefore, less number of collisions take place between molecules of a liquid as compared to gases.
Thus, we can conclude that particles collide in gas so, substance X is a gas.
