What is density?

Density is a physical property due the ratio between a substance's mass and volume. A physical property is something that does not change the chemical composition of the substance being observed. When you measure density, you place your subject on the scale to calculate mass, and then calculate volume by measuring the lengths and dividing the two.

Alternatively, you can measure density by using the displacement of liquid method, the volume of the liquid after the subject/object is immersed in the liquid, minus its original volume will give you substance's volume, then measuring mass on the scale. Since no chemical reaction is involved in measuring the density of a substance, it is considered a physical property.