Answer : Particles in the plasma move randomly, but particles in a solid vibrate in one place.
Explanation :
In plasma particles are observed to move randomly, whereas in case of solids they particles are placed in compact manner and they vibrate only in one place. In plasma the particles are not compactly placed therefore, the particles get chance to move in random direction.
Plasma particles in sun are observed to spread out which enable the movement of particles around in random direction.