Which of the following is NOT a physical property of hazardous materials?

The correct answer pertains to the distinction between physical and chemical properties of hazardous materials. Explosive limit refers to the concentration of a substance in the air that can lead to an explosion; this is a chemical property because it involves the reactivity and energy release of a substance under specific conditions. The explosive limit is related to how a material behaves in an explosive environment, which reflects a chemical reaction rather than a physical state.

On the other hand, vapor density, boiling point, and solubility are all considered physical properties. Vapor density indicates the mass of a substance compared to air, boiling point reflects the temperature at which a material transitions from liquid to gas, and solubility measures how well a substance dissolves in a solvent, typically water. All these properties describe the physical state, behavior, and interactions of a material without involving changes in chemical composition.