A solid is a state of matter where atoms or molecules are closely packed together and held in fixed positions by strong intermolecular forces. In a solid, the particles can only vibrate around their mean positions and cannot slide past each other. Solids have a definite shape and volume, and they are the most tightly packed state of matter. A liquid can have a different shape but same volume and a gas can change both its shape and volume .
The particles being locked in fixed positions indicates that the material is in a solid state, where they are closely packed and have a definite shape and volume. Solids display strong intermolecular forces that restrict particle movement. This is different from liquids and gases, which have looser structures that allow movement and change shape.
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