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

The boiling point is a prime example of a physical property because it describes a characteristic of a substance that can be observed or measured without altering its chemical composition. When a substance reaches its boiling point, it transitions from a liquid to a gas, but its chemical identity remains unchanged throughout this process.

Physical properties are typically those that can be assessed without the need for any chemical change, such as color, mass, volume, and density alongside boiling point. This makes boiling point a fundamental aspect of understanding substances in the context of physical chemistry, as it provides insight into how substances behave under different temperature conditions.

In contrast, the other options pertain to chemical properties, which involve a substance's ability to undergo changes that transform its basic chemical structure. Flammability indicates how a substance reacts in the presence of fire, chemical reactivity refers to how substances interact with each other, and tarnishing involves a reaction that changes the appearance and composition of the material over time.