Gas is defined as one of the three basic states of matter which is gas, liquid, and solid, and it has different properties from the rest of the states of matter, as the forces between molecules in the gaseous state of matter are very weak.The  

earth's atmosphere is a mixture of gases that consists of elemental nitrogen (N2)  

and oxygen (O2).This law describes how a gas expands as the temperature increases; conversely, a decrease in temperature will lead to a decrease in volume.Around 1787 Charles did an experiment where he filled five balloons to the same volume with different gases.Gases are important.2).3).