Class 6 Science Chapter 16 Air Around Us, Composition of Air, Importance of Air, Wind (For CBSE, ICSE, IAS, NET, NRA 2022)

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Air Around Us

  • Air is everywhere though we cannot see it but feel it.
  • For example, when the leaves of a tree rustle, we can hear the presence of air.
  • The layer of air around earth is known as the atmosphere.
  • Important uses of air:
    • Respiration
    • Combustion
    • Maintaining Temperature
    • Photosynthesis
    • Supplier of Energy
    • Flying of birds, bats, and insects
    • Generation of electricity by windmills

Composition of Air

Nitrogen

  • Nitrogen makes up 78.1 % of air around us and forms the largest component of air.
  • Plants use nitrogen for making protein.
  • It is not possible for plants to take nitrogen directly from the air.
  • Plants can take nitrogenous compounds from the soil as the nitrogen fixing bacteria living in soil helps in nitrogen fixation in soil.

Oxygen

  • It forms the second largest component of air.
  • It makes up 20.9 % of the air around us.
  • Living beings use oxygen for respiration purpose.

Carbon Dioxide and Argon

  • The remaining 0.03 % of air is composed of carbon dioxide, other gases, water vapour and dust particles.
  • Argon is 0.9 % .
  • Plant needs carbon dioxide to make food during photosynthesis.
  • The balance of carbon dioxide and oxygen in atmosphere is maintained by the green plants.

Air Supports Burning

Experiment

Air Supports Burning
  • In the above experiment tow burning candles have been taken and are placed on the table.
  • On of the burning candles is being covered with an inverted glass tumbler.
  • After sometime, the candle covered with glass tumbler blows out but the other candle continues to burn. This happened due to the absence of air in the glass tumbler. This shows that air supports burning.

Air is Dissolved in Water

Experiment

Air Dissolved in Water
  • In the above experiment some water has been taken in a beaker.
  • Heat is given on a tripod stand.
  • Tiny bubbles on the inside can be observed by looking carefully at the inner surface of the vessel even before water starts boiling.
  • On heating air dissolved in water escapes in the form of these bubbles.

Lump of Cotton Wool Shrink in Water

  • Air is filled among the gaps of cotton fibres in the lump of cotton wool.
  • The cotton lump becomes heavy as soon as water replaces the air from these gaps and shrinks due to removal of air gaps.

Plants and Animals Helping Other in Exchange of Gases

  • During respiration, animals take in oxygen and release carbon dioxide gas.
  • Plants utilize the carbon dioxide gas in the photosynthesis process for producing food and releasing oxygen in the atmosphere.

Wind Energy

  • Blowing air is called wind.
  • Wind possesses kinetic energy.
  • Wind energy is the kinetic energy possessed by the wind.

Uses of Wind Energy

  • To pump the ground water.
  • To generate electricity with the help of windmills.

Different Layers of Atmosphere

Different Layers of Atmosphere

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