Which of the following refers to a chemical property?

Reactivity is a fundamental chemical property because it describes how a substance interacts with other substances and its tendency to undergo chemical reactions. This aspect is inherently tied to the molecular structure and the bonds within the substance, determining how it can combine with or change in the presence of other chemicals. Understanding reactivity is crucial in various applications, such as in the funeral service industry, where different chemicals may be utilized during embalming or when considering the materials used in funeral products, as their interactions can affect safety and efficacy.

Other properties listed, such as color, boiling point, and density, are classified as physical properties. These physical properties can help identify substances and describe their state or appearance, but they do not involve a change in the chemical composition of the substance. For instance, boiling point refers to the temperature at which a substance changes from a liquid to a gas, while color and density describe characteristics that do not impact the substance's chemical identity.