Three States of Substance

The same substance can occur in nature in three states - in the form of gas, liquid, and a solid. So, if you preheat a piece of ice, it will melt and turn into water; If the water is heated even more, it will turn into steam. Steam is gaseous water; Ice is solid water.
Some substances are known to us in natural conditions in only one state. For example, we know air as a gas, mercury as a liquid, and iron as a solid. But these substances, as well as all substances without exception, can be obtained in all three states. Thus, liquids harden at sufficiently low temperatures, and evaporate at high temperatures. Gas can be turned into a liquid, and then into a solid. In laboratories, for example, now very often they deal with liquid air; Moleno get and the hard air. Mercury freezes at about forty degrees Celsius. Iron at very high temperatures can be turned into steam.
The main property of a gaseous body is the ability to dissipate in space; The gas, enclosed in a vessel of any size, is evenly distributed over this vessel.
On the contrary, the liquid always retains a certain volume. As for the form, it does not have fluid - it takes the form of the vessel into which we poured it.
A solid body has not only a certain volume, but also a definite shape. Only with the help of external forces - compression, stretching, impact - it is possible to change the shape of a solid body. However, despite the great external difference of the three states, the atomic and molecular composition of the substance is preserved in all three cases. Only the character of the mutual arrangement and motion of the particles changes.
Many scientists have not yet decided whether "plasma" is the fourth aggregate state of matter. On the one hand, plasma can not be attributed to already known three aggregate states , because it has fundamental physical properties. However, it has not yet been proved that absolutely any substance can be in a given "plasma" state.