Final answer:
The weight of pure vapor or gas compared to dry air is known as vapor density, which is a function of the molar mass of the gas.
Step-by-step explanation:
The weight of pure vapor or gas compared to the weight of an equal volume of dry air at the same temperature and pressure is known as the vapor density. This concept is important in the study of gases and their properties. The ideal gas law relates properties such as pressure (P), volume (V), temperature (T), and molar amount (n), and it indicates that the density of a gas is dependent on its molar mass. Thus, a gas with a lower molar mass will have a lower density than a gas with a higher molar mass when both are measured at the same temperature and pressure. On the other hand, chemical properties like flammability pertain to the substance's ability to undergo certain chemical reactions.