Yes, the density of a substance at a specific temperature is a physical property.

Here's why:

* Physical properties are characteristics of a substance that can be observed or measured without changing the substance's chemical composition.

* Density is a measure of how much mass is contained in a given volume. It's determined by the substance's inherent structure and doesn't involve any chemical reactions.

Therefore, the density of 1.738 g/cm³ at 20°C is a physical property because it describes a characteristic of the substance without altering its chemical makeup.