How is radiation defined?

Radiation is defined as energy that is emitted, transmitted, or absorbed in the form of waves or energetic particles. This definition encompasses a variety of types of radiation, including electromagnetic radiation (such as visible light, ultraviolet light, X-rays, and gamma rays) and particle radiation (such as alpha and beta particles). Understanding this concept is crucial, as it highlights radiation's role in various scientific fields, including physics, medicine, and environmental science.

In contrast, other options do not accurately represent the nature of radiation. The first option refers to matter that can be contaminated, which applies to hazardous materials but does not define radiation itself. The third option incorrectly identifies radiation as a type of hazardous chemical, while radiation can consist of energy and particles rather than being classified strictly as a chemical. The fourth option describes a physical state of matter rather than the concept of radiation, which specifically involves the movement and transmission of energy. Thus, the correct definition identifies radiation primarily as energy-related phenomena.