What is a physical property of a substance?

• A. A characteristic that can be observed or measured without changing the identity of the substance.
• B. A property that depends on the substance's chemical reactions.
• C. The mass of the substance when converted to energy.
• D. The temperature at which a substance boils.

Answer: (B)

Physical properties are those you can observe or measure about a substance without changing what it is. This means you can tell something about the substance by its appearance or behavior without turning it into something else—for example, its color, density, melting point, boiling point, or hardness.

The statement that describes a physical property matches this idea: it explains that you can observe or measure something about the substance without altering its identity. In contrast, chemical properties describe how a substance reacts with other substances or undergoes chemical changes, which involve making new substances. So they’re not physical properties. While boiling point is a physical property, the defining description here is the ability to observe or measure without changing the substance, which is why that option best captures what a physical property is.