Chemical reactions are not a physical property. Physical properties are characteristics of a substance that can be observed or measured without changing the substance's chemical composition. Examples of physical properties include color, density, melting point, and boiling point.

Chemical reactions, on the other hand, are processes in which substances undergo chemical changes, resulting in the formation of new substances with different chemical compositions. These reactions involve the breaking and forming of chemical bonds, which leads to changes in the properties of the substances involved.

Therefore, chemical reactions are considered chemical properties, as they describe how a substance interacts and transforms at a chemical level.