Air and Water

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Air is a mixture of gases. Its main components are nitrogen, oxygen, argon, carbon dioxide, inert gases, and water vapour.

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Air contains different gases together in varying amounts. Since these gases are not chemically combined into one substance, air is a mixture.

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Nitrogen is about 78.03% and oxygen is about 20.09% by volume. These two gases form the largest part of air.

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Oxygen is needed for respiration in almost all living beings. It also supports combustion, so burning happens easily in its presence.

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Oxygen takes part in respiration, burning, and rusting. It is chemically active and combines with many substances to form oxides.

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Liquid oxygen, called LOX, is used as an oxidant in rockets. It helps the fuel burn in space where air is not available.

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Nitrogen is the main constituent of proteins and helps living beings build body tissues. It also slows down the rate of oxidation and combustion caused by oxygen.

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Carbon dioxide is present only in a very small amount, about 0.033% by volume. Even in small quantity it is important for photosynthesis, but a large amount would disturb the balance of air.