Question

which medium(the glass, water, or diamond) is the most dense? and how do you know?

Answer 1

Density is mass per unit volume. So one easy way to measure the relative density of these three--water, glass, crystal--is to take an equal volume of all three and weight them. For example, take a diamond of size 1 cubic centimeter. Now take a piece of glass and some water of the same volume. Weight all three.

Which one will be the heaviest? Clearly it's one of glass and diamond, because if they were not denser than water, they would float in water, which they don't.

Answer 2

its diamond