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Air is a name for the mixture of gases present in the Earth's atmosphere. Compressed air is often used in scuba diving as a shallow water breathing gas and to inflate buoyancy devices. Compressed air is also used as the means of transmission of energy to pneumatic tools.
By volume, dry air is about:
With trace amounts of:
The amount of water vapor in the air varies considerably depending on weather, climate, and altitude. See Humidity.
The molecular mass of air is approximately 28.96443 g/mole (molecular weight of standard air - CRC, 1983).
The density of air is about approximately 0.6113 kgm-3
Average pressure of air is approximately 101.325 kPa