Clearer Question: What is the three states of matter in science
Solid, is one of the three maters in science. Solids are firm and stable in shape, it is not hollow.
Liquid, is one of the three matters in science. Liquids changes shape depending on it's container.
Gas, finally is one of the three matters in science. Gases conforms to a shape of a container also, it has low density and velocity.