Answer: Extensive properties such as the mass, volume and entropy of systems are additive for subsystems, useful for identifying a substance because the substance may be present in any physical properties. Some intensive properties, such as temperature, refractive index and density, aren't useful either.
Explanation: According to scientific studies, Physical properties of materials and systems can often be classified as being either intensive or extensive, according to how the property changes when the size (or extent) of the system changes. Based on IUPAC classification, an intensive quantity is one whose magnitude is independent of the size of the system whereas an extensive quantity is one whose magnitude is additive for subsystems. This explains the corresponding mathematical ideas of mean and measure, respectively.