Gaseous State
The matter in gaseous state has neither definite volume nor shape.
Examples : Air, oxygen, nitrogen, hydrogen, ammonia, carbon dioxide, compressed natural gas (CNG) etc.
*Properties of Gases
(a) Gases neither have a definite shape nor a definite volume : Gases do not have a definite shape, but they acquire the shape of the vessel in which they are placed.
Similarly, gases do not have a definite volume, but attain the volume of container to which they are transferred.
(b) Gases have maximum fluidity and least rigidity : The gases have high fluidity (property to flow) and least rigidity (tendency to maintain shape) due to large inter particle space and weak inter particle forces of attraction in them.
(c) Gases are highly compressible : The gases are highly compressible due to large inter particle spaces in them. Due to high compressibility, large volume of a gas can be compressed into a small cylinder and transported easily. e.g. L.P.G. gas & O2 supplied to hospitals in cylinders is compressed gas. Similarly these days, compressed natural gas (CNG) is used as a fuel in vehicles.
Gases are highly compressible while liquids are almost incompressible, while solids are completely incompressible.