<P> Classically, states of matter are distinguished by changes in specific heat capacity, pressure, and temperature . States are distinguished by a discontinuity in one of those properties: for example, raising the temperature of ice produces a clear discontinuity at 0 ° C as energy goes into phase transition, instead of temperature increase . The classical states of matter are usually summarised as: solid, liquid, gas, and plasma . In the 20th century, increased understanding of the more exotic properties of matter resulted in the identification of many additional states of matter, none of which are observed in normal conditions . </P> <Ul> <Li> Solid: A solid holds a definite shape and volume without a container . The particles are held very close to each other <Ul> <Li> Amorphous solid: A solid in which there is no far - range order of the positions of the atoms . </Li> <Li> Crystalline solid: A solid in which atoms, molecules, or ions are packed in a regular order . </Li> <Li> Plastic crystal: A molecular solid with long - range positional order but with constituent molecules retaining rotational freedom . </Li> <Li> Quasi-crystal: A solid in which the positions of the atoms have long - range order, but is not in a repeating pattern . </Li> </Ul> </Li> <Li> Liquid: A mostly non-compressible fluid . Able to conform to the shape of its container but retaining a (nearly) constant volume independent of pressure . <Ul> <Li> Liquid crystal: Properties intermediate between liquids and crystals . Generally, able to flow like a liquid but exhibiting long - range order . </Li> <Li> Disordered hyperuniformity: A state similar to a liquid and a crystal in properties . Like a crystal, its particles over large distances exhibit uniform density and are unable to compress . Like a liquid, its particles at smaller distances display the same physical properties in all directions . </Li> </Ul> </Li> <Li> Gas: A compressible fluid . Not only will a gas conform to the shape of its container but it will also expand to fill the container . </Li> <Li> Plasma: Free charged particles, usually in equal numbers, such as ions and electrons . Unlike gases, plasmas may self - generate magnetic fields and electric currents, and respond strongly and collectively to electromagnetic forces . </Li> </Ul>

How many main states of matter are there
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