Science: Air and Water: Importance of Various Components of Air (For CBSE, ICSE, IAS, NET, NRA 2022)

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Water is the most abundant and renewable natural resource. It covers about three quarters of earth՚s surface. Water occurs in nature in the free state as well as in the combined state. The different properties of water make it useful and essential in our daily life.


Air is a mixture of gases. The composition of dry air at sea level is given in table

Components of Air

Components of Air
GasComposition (% by volume)
Nitrogen (N2)78.03
Oxygen (O2)20.09
Argon (Ar)0.94
Carbon dioxide (CO2)0.033
Inert gases (Neon, Helium, Crypton, Xenon: Ne, He, Kr, Xe)0.002

Importance of Various Components of Air


Oxygen is one of the major components of air and life is not possible without oxygen.

The importance and utility of oxygen is given below:

  • Oxygen is necessary for respiration in almost all living beings.
  • It is the necessity of combustion and therefore materials burn easily in the presence of oxygen.
  • Oxygen from air gets dissolved in water which keeps the water and aquatic life fresh.
  • Oxygen cylinders are carried by climbers, during high altitude climbing, by aviators during high altitude flying and firemen during firefighting.
  • Rusting of iron takes place in the presence of oxygen and water.

Medical Uses

  • Oxygen is given to the patients suffering from asthma or gas poisoning and for artificial respiration in hospitals.
  • A mixture of oxygen and nitrous oxide is used as anesthesia in surgical operations.

Industrial Use

  • In steel industry: Impurities present in iron are removed by burning in presence of oxygen.
  • For cutting and welding purposes: Oxygen is mixed with hydrogen (hydrogen torch) or acetylene (oxyacetylene torch) . These mixtures are burnt to produce very high temperatures and are used for cutting metals and for welding.
  • Oxygen is also used for the manufacture of sulphuric acid from Sulphur and nitric acid from ammonia (NH3) .

Harmful Effects of Oxygen

Corrosion means deterioration of metals by an electrochemical process. The most common example of corrosion is the rusting of iron. Oxygen gas and water must be present for iron to rust. Similarly, articles made of other metals like aluminum and copper also corrode slowly in the presence of oxygen. Oxygen combines with almost all elements to form oxides.


  • Nitrogen is the main constituent of proteins.
  • A number of amino acids containing nitrogen join together to form a protein. Proteins build the body.
  • Enzymes which act as catalyst in biochemical reactions occurring in the body are mostly proteins.

Main uses of nitrogen are as follows:

Nitrogen subdues the activity of oxygen. If concentration of oxygen in air is increased, processes like metabolism, combustion and corrosion are speeded up and this shall have a harmful effect. Hence, due to the presence of nitrogen, oxidation of food and combustion of fuel occur at a moderate rate.

Carbon Dioxide

  • The percentage of carbon dioxide in air varies from place to place.
  • During photosynthesis, plants absorb carbon dioxide and water vapour from atmosphere and convert into carbohydrates (Sugars) in the presence of chlorophyll and sunlight.
  • Carbon dioxide dissolves in water to form carbonic acid H2CO3 which reacts with rocks that contain calcium carbonate (CaCO3) or magnesium carbonate (MgCO3 to form Ca (HCO3)2 and Mg (HCO3)2 salts. These salts give the taste of natural water and also supply Ca2 + and Mg2 + ions to the plants which are necessary for their growth.
  • It is also used in food preservation. When stored in an atmosphere of CO2, the grains are prevented from being destroyed by insects. Can you give a reason?
  • Solid CO2, which is known as dry ice, is used as refrigerant.
  • Dissolved in water, CO2 is used in the preparation of soft drinks. The effervescence that comes out when we open a soft drink bottle is carbon dioxide. CO2 is used in fire extinguishers.

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