Which of the following is NOT one of the four classes of chemical hazards?

The classification of chemical hazards typically involves four primary categories: flammability, toxicity, corrosivity, and reactivity. Each of these classes highlights a specific risk associated with chemicals.

Flammability refers to the ability of a chemical to ignite and start a fire, which poses significant safety risks in handling and storage. Toxicity indicates the degree to which a substance can damage an organism's health, leading to harmful effects from exposure, whether through inhalation, ingestion, or skin contact. Corrosivity involves the ability of a chemical to destroy or damage living tissue or severely corrode materials upon contact. These classifications play crucial roles in risk assessment and management in various environments.

Volatility, while an important property of some chemicals, does not represent a class of hazards in the same context as the others. Volatility describes the tendency of a substance to vaporize, which can lead to inhalation risks but does not encompass the broader harm types that the main classes signify. Hence, volatility is distinct from the recognized classes of chemical hazards.