Question

how can we tell that the intermolecular spaces in a liquid are greater than in case of a solid??

Answer 1

The forces of attractions between the molecules in liquid are weaker than in solids. This can be confirmed by the compressibility. Liquids are more compressible than solids. Also the binding energy between the molecules are not strong enough to stop the motion of the molecules altogether, with the result that molecules can move from one place to another. Thus they have larger intermolecular spaces among molecules.