Final answer:
Density, like all physical properties, can be measured or observed and is influenced by temperature and pressure changes. This relationship is especially evident in gases, but also applies to solids and liquids.
Step-by-step explanation:
When we consider density as a physical property, we can look for two characteristics that it shares with all other physical properties. Since density is indeed a physical characteristic of matter, it, like other physical properties, can be measured/observed and depends on temperature and pressure.
All physical properties, including density, can be observed or measured without changing the identity of the substance. Additionally, properties such as density are affected by temperature and pressure changes. This means that as the temperature or pressure changes, so might the density of a substance, indicating a direct relationship between these variables.
For example, the density of gases is known to change with temperature changes, showing a direct relationship where the volume of a gas increases with temperature and decreases when the temperature is lowered, assuming constant pressure. The same principle applies to solids and liquids, although the effect of temperature and pressure on their densities is typically less pronounced than in gases.