In hazardous materials terminology, how is radioactivity defined?

Radioactivity is defined as the emission of radiation from unstable atomic nuclei. This phenomenon occurs when an unstable nucleus releases energy in the form of radiation, which can include alpha particles, beta particles, and gamma rays. This process is a natural characteristic of certain elements, particularly heavy ones like uranium and radium, and it is a fundamental concept in nuclear physics and chemistry.

Understanding radioactivity is crucial in hazardous materials management because it poses specific risks, such as contamination and radiation exposure, that require special handling, storage, and emergency response protocols. The other options, while related to hazardous materials, describe different aspects of chemical safety and toxicity that do not pertain directly to the specific behavior of radioactive materials.