Liquids generally undergo greater thermal expansion than solids.

Here's why:

* Particle arrangement: In solids, particles are tightly packed and held together by strong intermolecular forces. This restricts their movement and limits expansion. Liquids have weaker intermolecular forces and their particles are more loosely packed, allowing for greater freedom of movement and expansion.

* Intermolecular forces: The intermolecular forces in solids are generally stronger than those in liquids. When heat is applied, the molecules in solids have less freedom to move apart because of these strong forces.

Example: Consider water. When water is heated, it expands as a liquid. But when water freezes into ice (a solid), it actually expands because of the rigid crystalline structure formed by the water molecules.

Exceptions: There are some exceptions to this general rule. Certain materials like rubber exhibit high thermal expansion due to their unique molecular structure. However, in general, liquids show greater thermal expansion than solids.