Which phase of matter is characterized by a fixed shape and volume?

The phase of matter characterized by a fixed shape and volume is a solid. In a solid, the particles are closely packed together in a structured arrangement, resulting in a definite form that does not change easily. This means that solids maintain their shape regardless of the container they are in. The strong intermolecular forces between the particles in solids prevent them from moving freely, which is why solids do not flow like liquids or gases.

In contrast, liquids have a defined volume but take the shape of their container, meaning they do not have a fixed shape. Gases have neither a fixed shape nor a fixed volume, expanding to fill any space available to them. Plasma, which is another phase of matter, consists of highly energized particles with sufficient energy to break free from the bonds that hold them together, also lacking a defined shape and volume. Therefore, the properties of solids make them unique in maintaining both shape and volume compared to liquids, gases, and plasma.