Final answer:
The three states of matter are solid, liquid, and gas. Solids have a fixed shape and volume, liquids have a fixed volume but no fixed shape, and gases have neither a definite shape nor volume.
Step-by-step explanation:
The three phases or states of matter are solid, liquid, and gas. These are different forms that matter can take, depending on temperature and pressure. Solids have a definite shape and volume, liquids have a definite volume but take the shape of their container, and gases have no definite shape or volume and will expand to fill any container they are in.
In the solid phase, particles are in close contact with each other and are arranged in a fixed, rigid structure. They can only vibrate in place, which means solids have a definite shape and volume. In the liquid phase, the particles are still in contact, but they can move around and slide past each other, giving liquids a fixed volume but no fixed shape. Lastly, in the gas phase, the particles are much more spread out and move freely, resulting in neither a definite shape nor a definite volume.
These states can change from one to another through processes such as melting (solid to liquid), freezing (liquid to solid), vaporization (liquid to gas), and condensation (gas to liquid).