Why liquid cannot be compressed to solids?

Answer 1

In liquid state as the temperature is higher the atoms or molecules are at random motion with greater speed. Hence the field coverage of protons will be wide and there will be repulsive force dominant. Hence as we compress the liquid this repulsive force becomes more as the distance gets reduced and so liquids generally are incompressible.

In fact you can, (depending on the temp) but the conditions are frequently "unearthly". See papers on the possible core of Jupiter.

add. The inner core of the earth has a temperature about the same as that of the surface of the Sun - 57 000 deg C. But the inner core is solid because of the great pressure. Moving outwards from the core, we next meet the outer core, essentially the same extreme temperature, but it is liquid now because of the reduced pressure.

Answer 2

Liquid cannot be compressed into a solid because the atoms or molecules in a liquid are already in close contact with each other and moving freely. When pressure is applied to a liquid, the atoms or molecules can be pushed closer together, but they will still maintain their fluid-like behavior. In order to turn a liquid into a solid, additional energy is needed to rearrange the atoms or molecules into a more ordered and fixed structure.