What are the three states of matter?

The three states of matter are solid, liquid, and gas because these are the most commonly observed forms of matter in our everyday lives. In a solid state, particles are closely packed together in a fixed arrangement, which gives solids a definite shape and volume. In a liquid state, particles are still close together but can move past one another, allowing liquids to take the shape of their container while maintaining a fixed volume. In a gaseous state, the particles are far apart and move freely, meaning gases will expand to fill the entire volume of their container without a fixed shape.

Other options include states that do not represent the fundamental states of matter. Plasma, for example, is considered the fourth state of matter, typically found in stars, but it is not one of the primary three states observed under normal conditions on Earth. A vacuum refers to a space devoid of matter and is not a state of matter itself. Electricity is a form of energy, not a state of matter, so it does not fit into this classification. Focusing on the three fundamental states—solid, liquid, and gas—helps to simplify the understanding of matter in various physical forms.