But these three basic properties of materials expressing in gas liquid and solid have difference in quantity and quality In the same volume the number of gas molecules is less than that of liquid molecules and the number of liquid molecules is less than that of solid molecules, so the distance between gas molecules is longer and the gravitation is less than that of others, and liquid take the second place The macroscopical appearance caused by these microcosmic differences are The solid has definite volume and shape The liquid has definite volume but have indefinite shape The gas has neither definite volume nor definite shape9 But these three basic properties of materials expressing in gas, liquid and solid have difference in quantity and quality. In the same volume the number of gas molecules is less than that of liquid molecules and the number of liquid molecules is less than that of solid molecules, so the distance between gas molecules is longer and the gravitation is less than that of others, and liquid take the second place. The macroscopical appearance caused by these microcosmic differences are ： The solid has definite volume and shape. The liquid has definite volume but have indefinite shape. The gas has neither definite volume nor definite shape