Gases are one of the three fundamental states of matter, along with solids and liquids. They are characterized by their low density and high fluidity, which means that they can easily flow and expand to fill the available space.
The molecules or particles in a gas are in constant, random motion, moving freely throughout the space they occupy. This constant movement and the absence of strong intermolecular forces between particles contribute to the indefinite shape and volume of gases.
Unlike liquids and solids, which have a fixed volume and shape determined by their molecular arrangement, gases take the shape and volume of the container they are in. They fill the entire available space, expanding or contracting as needed.
Examples of gases include air, helium, nitrogen, oxygen, and hydrogen. These substances exist as gases under normal Earth conditions of temperature and pressure.
