During which processes does the space between particles tend to increase

Explanation:

In a solid, molecules are held together by strong intermolecular forces of attraction. As a result, they are unable to move from their initial place but they can vibrate at their mean position.  

Hence, in solid substances the molecules have low kinetic energy.

Whereas in liquids, the molecules are held by less strong intermolecular forces of attraction as compared to solids. Due to which they are able to slide past each other. Hence, they have medium kinetic energy.

In gases, the molecules are held by weak Vander waal forces. Hence, they have high kinetic energy due to which they move 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, we can conclude that in gaseous phase the space between particles tend to increase.

Melting between solid and a gas. Sublination when the solid turns to gas. And when a liquid turns to a solid.

Explanation: Gas has the most space between particles, then gas and then solid. So gas will always have the greatest distance. liquid will have a greater distance than a solid.