Which statement correctly defines physical properties?

• A. They can be observed only by changing the composition of the object
• B. They can be observed without changing the composition of the object
• C. They describe a chemical reaction
• D. They require altering the identity of the substance

Answer: (B)

Physical properties are characteristics you can observe or measure about a material without changing what it is made of. This means you can learn about them by testing or observing, while the substance keeps its chemical identity intact. Examples include color, density, melting point, boiling point, hardness, and electrical conductivity. These are things you can determine without making or breaking chemical bonds.

The statement fits this idea because it says these properties can be observed without changing the composition. In contrast, descriptions that rely on chemical reactions or changing the substance into something else describe chemical properties or chemical changes, where the identity of the material does change. For instance, a substance’s reactivity with acid or its flammability shows how it behaves in a chemical reaction, not just how it appears or behaves without reacting.