Gas :
A state of matter that has no definite shape as well as no definite volume is called gas: it occupied all the space container which it is kept.
Liquid :
A state of matter that has a definite volume but no definite shape is called liquid. it occupies or attains the shape of the container in which it is kept.
Solid:
A state of matter that has both definite shape and volume is called solid.
Liquids are less common than solids, gases, and plasmas. The reason is that the liquid state of any substance can exist only within a relatively narrow range of temperature and pressure.
the same substance may exist in three states. for example, water in the form of ice is solid; in the form of steam is gas, while a usual form of water is liquid.
it is the inter-molecular distances or spaces between the molecules, which makes difference among the three states. in solids, the molecules are closely packed with one another and have minimum inter-molecular distance. in gases, the molecules are free from one another and have very large inter-molecular distance. in liquids the situation is intermediate. they have large inter-molecular distance as compared to solids but much less than gases.
