Solids
Explanation:
Solids have definite shapes and definite volumes. The forces of attraction between the molecules of a solid substance are strong and the intermolecular spaces are very small. Due to this, the motion of molecules within a solid substance are very difficult that they only vibrate in their positions.
For liquids, they have definite volumes and indefinite shapes. The forces of attraction between the molecules of a liquid are intermediate and the the intermolecular spaces are intermediate as well. Due to this, the motion of molecules within a liquid substance is not as difficult as it is within solids.
Finally, for gases, they have indefinite shapes and indefinite volumes. The forces of attraction between the molecules of a gas are weak and the intermolecular spaces are large. Due to this, the motion of particles of gas is very easy.
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