Answer: in a solid, the particles are closely packed together and have fixed positions. They vibrate or oscillate around their equilibrium positions, but they do not move from one position to another. This means that the particles in a solid do not change their relative positions.
Explanation: To understand this better, imagine a group of people standing shoulder to shoulder in a line. Each person represents a particle in the solid. Even though they may wiggle or shake slightly, they remain in the same position relative to each other. They don't swap places or move around freely like particles in a liquid or gas.
The movement of particles in a solid is limited to vibrations within their fixed positions. These vibrations increase with temperature, which is why solids expand when heated. The increased thermal energy causes the particles to vibrate more vigorously, pushing them slightly apart and causing the solid to expand.
In summary, the particles in a solid are tightly packed and have fixed positions. They vibrate around their equilibrium positions, but they do not move from one position to another like particles in a liquid or gas.