Mentos reacts to coca-cola because of the sugars and then they expand which causes the soda to explode out of the open container. this is a chemical reaction because it cause the sugars to expand which you can't see happen.
The answer mass of copper sulphate is
46g
Density = mass / volume
Mass = 5 kg
Volume = 50 cm³
d = 5 / 50
d = 0,1 kg/cm³
