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gas
state of matter
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Also known as: gaseous state
heated air expands
gas, one of the three fundamental states of matter, with distinctly different properties from the liquid and solid states. The remarkable feature of gases is that they appear to have no structure at all. They have neither a definite size nor shape, whereas ordinary solids have both a definite size and a definite shape, and liquids have a definite size, or volume, even though they adapt their shape to that of the container in which they are placed. Gases will completely fill any closed container; their properties depend on the volume of a container but not on its shape. Gases ...(100 of 12578 words)