15. AIR AROUND US
Chapter-reviews:
- The air contains nitrogen 79%, oxygen 21%, carbon dioxide 1%, some other gass, water vapour. Air also contains dust particles and smoke.
- Oxygen is the gas, which is essential for respiration.
- Air support burning.
- Moving air is called wind.
- Air occupies space.
- The presence of water vapour in air is important for the water cycle in nature.
- The air contains water vapour.
- The envelope of air that surrounds the earth is known as atmosphere.
- Atmosphere is essential for life on earth.
- Aquatic animals use dissolved air in water for respiration.
- Plants and animals depend on each other for exchange of oxygen and carbon dioxide from air.
- Nitrogen gas is present in atmosphere in large amount.
- Animals and plants both use oxygen for respiration and gaseous exchanges take place among themselves.
- Animals cannot live without plants. Similarly, plants can not survive for long without animals.
- Windmills are also used to generate electricity. which run by the help of air.
- Air also helps in the dispersal of seeds and pollen of flowers of several plants.
- Air plays an important role in water cycle.
