Why do liquid have a fixed volume?

Answer 1

Liquids have a fixed volume because the amount of liquid you have will never change in size no matter what size or shape the container is. In Layman's terms, you dont get more or less water by changing the cup it is in; it simply changes shape.

Liquids are similar in density to solids; in both of these phases the constituent molecules or atoms are close enough to effectively be in contact (on the atomic level, being in contact means that the electrons of one atom or molecule are close enough to the electrons of another atom or molecule to repel them strongly enough that they are not going to get any closer without really extreme force being applied). The atoms or molecules which are not getting any closer to each other are also not gettting any farther apart, because of whatever chemical bond has caused them to be in that phase (solid or liquid). This differs from the gas phase in which atoms or molecules are quite far apart, and therefore have lots of room to be squeezed closer to gether if you compress the gas, and equally well they can easily expand without limit if they are given more room in which to expand.

Answer 2

Because it's molecules are still under strong intermolecular forces,so they are not easily compressible.