Answer: Hello! Here we have a cube, with a mass of 10g and a side length of 2.5cm.
First we want to determine the volume.
The volume of a cube, is equal to his cubic side length, where L is the side length:
So

So the volume of the cube is 15.625 cubic centimeters.
Now we want to calculate te density of the material, as you know:

This means that the density is 0.64 grams per cubic centimeter.