Physical Properties

States of Matter

3. Gas

Try to breathe in and breathe out. Do you know that gases enter and leave your body as you breathe in and out?

Matter that is in the gas state does not have definite shape, size, and volume. Like liquids, a gas takes the shape of its container. This is because the molecules of a gas are arranged wide apart from each other so they are able to move around and fill the shape of a container. You cannot see most gases, but you can feel or sometimes smell them. The oxygen in the air that you breathe is an example of a gas.

Mass

Mass is the measure of the amount of matter in an object. Mass and weight are often confused. Mass is the amount of matter in the object, while weight is the amount of force acting on the object because of gravity. The mass of an object remains the same regardless of where the object is, while the weight of an object changes depending on the strength of the pull of gravity on the object.

The amount of gravity varies in different places. Earth has greater gravity than the moon. This is why your weight on the moon is only 1/6 of your weight on Earth. Suppose you weigh 54 kilograms (kg) on Earth. Divide the figure by 6 and you get 9 kg, which will be your weight on the moon.