Ch – 15 Air Around Us

  • Air is present everywhere.
  • Air occupies space.
  • It is a mixture of gases.
  • The gases in air are mainly nitrogen, oxygen, small amount of carbon dioxide, and many other gases.
  • Major part of air consists of nitrogen and oxygen, approximately 99%.
  • The layer of air around the earth, which extends up to several kilometres is known as atmosphere.
  • The presence of water vapour in air is important for the water cycle in nature.
  • Air is important for respiration.
  • Mountaineers carry oxygen cylinders with them, because as we move higher, the air gets rarer.
  • Oxygen supports burning while nitrogen does not.
  • Burning releases carbon dioxide in the gas which may cause suffocation.
  • Burning of fuel produces smoke which contains harmful gases.
  • The presence of dust particles in air varies from time to time, and from place to place.
  • We inhale air when we breathe through our nostrils. Fine hair and mucus are present inside the nose to prevent dust particles from entering our respiratory system.
  • The balance of oxygen and carbon dioxide in the atmosphere is maintained through respiration in plants and animals and by the photosynthesis in plants. This shows the interdependence of plants and animals.
  • Moving air is known as wind.
  • Wind helps to move blades of windmills.
  • Air helps in movement of sailing yachts, gliders, parachutes and aeroplanes.
  • Air helps in movement of birds and insects.
  • Air helps in dispersal of seeds and germination.

Published by Priya Prakash

In the midst of winter, i found there was within me an invincible summer ~ Albert Camus

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