According to the kinetic particle theory of matter the particles in solids
1. Are tightly packed in an orderly manner;
2. Are held together by strong attractive forces;
3. Have just enough kinetic energy to vibrate or rotate about their fixed positions
4. Cannot move freely
Solids cannot be compressed as there is very little space between the particles; they are packed close to each other. The distance between the particle is minimum. Hence they have fixed volume.