Final answer:
Melting points and boiling points are physical properties as they can be observed or measured without changing the identity of the substance.
Step-by-step explanation:
Melting points and boiling points belong to the category of physical properties. These are characteristics that can be observed or measured without changing the substance's identity. Physical properties include various attributes such as color, density, hardness, as well as melting and boiling points. On the other hand, chemical properties describe a substance's ability to undergo a chemical change, which involves transforming into a different substance. Examples of chemical properties include flammability and reactivity. Since melting and boiling points can be determined without the substance undergoing a chemical change, they are not classified as chemical properties.
Physical properties are often determined by the type of intermolecular forces present in a substance. For instance, substances with similar molar masses might display very different boiling points due to variations in these forces. Thus, boiling and melting points provide important information regarding the physical characteristics and behavior of substances without altering their chemical composition.