Final answer:
Flammability is a chemical property as it describes a substance's tendency to burn or ignite, which involves a chemical reaction. Density, boiling point, and melting point are physical properties because they involve measurements that do not change the substance's chemical composition.
Step-by-step explanation:
The question asks about the distinction between chemical and physical properties of matter. A chemical property is a characteristic that describes how a substance can change to form a new substance during a chemical reaction, such as flammability or reactivity with acids. Comparatively, a physical property is a characteristic that can be measured or observed without changing the substance's chemical identity, such as density, melting point, and boiling point.
In response to the exercise, flammability is a chemical property, because it describes a substance's ability to ignite and burn, which involves a chemical change, converting the substance into different chemical compounds like carbon dioxide and water. On the other hand, melting point, boiling point, and density are all physical properties, as they do not involve changing the substance's chemical makeup when they are measured or observed.