Which of the following is not a physical state of matter?

Energy is not considered a physical state of matter. Instead, energy refers to the capacity to do work or produce change and is often associated with the ability of physical states (solid, liquid, gas) to undergo transformations. The three primary physical states of matter—solid, liquid, and gas—are characterized by distinct properties related to the arrangement and behavior of particles. Solids have a fixed shape and volume, liquids have a defined volume but take the shape of their container, and gases have neither fixed shape nor volume, expanding to fill their container. Understanding these states helps in grasping fundamental concepts in physics and chemistry, as they describe the physical form that substances can take under varying conditions.