Water displacement. You fill a graduated cylinder with an amount of water, place the object inside the graduated cylinder, and then measure the new water level. The change in volume of the water is the volume of the object, assuming the object was completely submerged.
Gases have three characteristic properties:
(1) they are easy to compress,
(2) they expand to fill<span> their containers, and
(3) they occupy far more space than the liquids or solids from which they form.</span>
Chemical because when you eat, the food give off a chemical bond