Thermal expansion in solids is ________than liquids and gases.

Explanation

**Step-by-Step Solution:**

1. **Understanding Thermal Expansion**: Thermal expansion refers to the increase in size or volume of a substance when it is heated. When materials are heated, their particles move more vigorously and tend to occupy a larger space.

2. **Comparison of States of Matter**:
- **Solids**: In solids, the atoms and molecules are closely packed together. This close arrangement means that when solids are heated, they expand, but the expansion is limited due to the strong intermolecular forces holding the particles together.
- **Liquids**: In liquids, the particles are less tightly packed than in solids, allowing for more movement. Therefore, when liquids are heated, they expand more than solids.
- **Gases**: In gases, the particles are far apart and move freely. This means that gases can expand significantly when heated, more than both solids and liquids.
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