1. Calculate the mass of a liquid with a density of 3.2 g/mL and a volume of 25 mL.
2. An irregular object with a mass of 18kg displaces 2.5 L of water when placed in a large overflow container. Calculate the density of the object.
3. A graduated cylinder has a mass of 80 g when empty. When 20 mL of water is added, the graduated cylinder has a mass of 100 g. If a stone is added to the graduated cylinder, the water level rises to 45 mL and the total mass is now 156 g. What is the density of the stone?