Gas is one of the four fundamental states of matter, alongside solid, liquid, and plasma. In the gas state, a substance has a low density and can expand to fill the volume of its container. Unlike solids and liquids, gas particles are much further apart and move freely, allowing them to occupy any available space.
Gases have several key characteristics:
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Indefinite Shape and Volume: Gases do not have a fixed shape or volume. They take the shape of their container and expand to fill it.
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Low Density: Gases are less dense than solids and liquids, as the particles are farther apart.
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Compressibility: Gases can be compressed into smaller volumes, as there is considerable space between particles.
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Effusion and Diffusion: Gas particles can move through openings (effusion) and spread out to evenly fill a space (diffusion).
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Pressure: Gas exerts pressure on the walls of its container due to the collisions of its particles with the container.
Common examples of gases include oxygen, nitrogen, carbon dioxide, and noble gases like helium and neon. Gases can exist under various conditions of temperature and pressure, and they are often studied in fields such as chemistry, physics, and engineering.