Gas
From Wikipedia, a free encyclopedia written in simple English for easy reading.
A gas is one of the states of matter. Gases are "fluid". This means that they can freely move and expand to fill a container. They can be pushed into a smaller volume, or expanded into a greater volume. A gas has a very low density, because the molecules or atoms in the gas are far apart.
The word gas can also refer to specific gases, such as natural gas, laughing gas (which is nitrous oxide), or acetylene.
Sometimes people use gas as a shorter name for gasoline (which is called petrol in some counties), or for the gases used in chemical warfare, like mustard gas.
