This is a measure of mass per unit volume.

Density

Explanation:

Density is defined as the mass per unit volume. It is the ratio between the mass and the volume of a substance. It does not matter how large or small a sample of matter is, the same substance will always have the same density, because of this. The ratio between the mass and volume remains the same.

3 hours because it is a decent distance.

answer; talc and gypsum;