Answer:
The kinetic molecular theory explains the expansion of a solid material with increases of temperature as basically the result of molecules moving a little farther apart.
Step-by-step explanation:
The kinetic-molecular theory explains the changes of state in the following way: When a solid is heated, its particles increase their kinetic energy, so that the vibration becomes more and more intense until, having reached the melting temperature, they become so weak that the particles acquire freedom of movement, that is, if we increase the temperature of a solid material system, its molecules will move faster and the average distance between them will increase, the cohesion forces decrease and there will come a time when these forces are incapable to keep the molecules in fixed positions, the molecules can move.