What term describes the ability of two or more substances to mix with or dissolve into each other?

• A. Miscibility
• B. Solubility
• C. Reactivity
• D. Density

Answer: (A)

Miscibility describes the ability of two or more liquids to mix with each other to form a single, uniform phase. When substances are miscible, they blend in any proportion, which means a spill of one will merge with the other rather than separate into layers. For example, water and ethanol mix completely, so a spill of ethanol will blend with water. In hazmat scenarios, knowing miscibility helps predict how a spill will behave, how it will spread, and what containment or cleanup steps are needed. This is different from solubility, which is about how well a substance dissolves in a solvent (often describing a solid or liquid dissolving in another liquid) and doesn’t necessarily imply two liquids will mix in all proportions. Reactivity concerns chemical reactions between substances, and density is simply mass per volume, not about mixing behavior.