Which is a physical property?

Which is a physical property?

• A. Flammability
• B. Odor change during reaction
• C. Density
• D. Reactivity with acid

Answer: (C)

Distinguishing physical properties from chemical properties is what this item focuses on. A physical property is something you can observe or measure about a material without changing its identity. Density fits this because you can determine it from mass and volume without transforming the substance—the material stays the same while you measure how much mass sits in a given space. The other options describe changes to the material’s composition: flammability means the substance can burn (a chemical change occurs), an odor change during a reaction indicates new molecules are formed (chemical change), and reactivity with acid shows the material undergoes a chemical reaction. So density is the physical property here.

Distinguishing physical properties from chemical properties is what this item focuses on. A physical property is something you can observe or measure about a material without changing its identity. Density fits this because you can determine it from mass and volume without transforming the substance—the material stays the same while you measure how much mass sits in a given space. The other options describe changes to the material’s composition: flammability means the substance can burn (a chemical change occurs), an odor change during a reaction indicates new molecules are formed (chemical change), and reactivity with acid shows the material undergoes a chemical reaction. So density is the physical property here.