Which of the following is a physical property?

• A. Reactivity with acid
• B. Color
• C. Flammability
• D. Heat of combustion

Answer: (B)

Color is a physical property because it describes how a substance looks and can be observed without changing its identity. You can see the color and still have the same material, so no chemical reaction has occurred. In contrast, reactivity with acid involves a chemical change where the substance’s composition is altered; flammability and heat of combustion involve burning, which is a chemical process that breaks and forms bonds and releases energy. So color fits the definition of a physical property.