Which property can indicate the purity of a substance?

Density is a key property used to indicate the purity of a substance because it is a characteristic physical property that remains consistent for pure substances at a given temperature and pressure. When a substance is pure, it will have a specific density that can be measured and compared to standard values. If the density of a sample deviates from the known density of the pure substance, it may indicate the presence of impurities or a mixture.

In contrast, luster refers to the way light reflects off a substance's surface and is more related to the visual appearance of materials rather than their purity. Volume, which measures the space a substance occupies, can change with temperature and pressure and doesn't provide information about the chemical composition. Temperature, while it can affect the state of matter or the behavior of a substance, does not directly indicate purity. Therefore, density serves as a reliable indicator of substance purity due to its consistency for pure materials.