Which of the following is an example of a physical property?

• A. Density
• B. Reactivity With Acid
• C. Flammability
• D. Combustibility

Answer: (A)

Physical properties are characteristics you can observe or measure without changing the substance into something else. Density fits this because it describes how much mass is in a given volume and you determine it by measuring mass and volume, leaving the material itself unchanged. The other options describe chemical properties, which involve how a substance reacts to become different substances or how it behaves during burning. Reactivity with acid shows a chemical reaction that alters composition, while flammability and combustibility describe burning, which is a chemical change. So density is the example of a physical property.