Revision Notes of Ch 15 Air Around Us Class 6th Science

Topics in the chapter

  • What is air?
  • Composition of Air
  • How does oxygen become available for all living beings? 
  • Properties of air

What is air?

→ Air is a mixture of gases and dust particles. It is a clear gas in which living things breathe and live.

→ Air is a matter it has volume and mass. It creates atmospheric pressure.

→ In vacuum there in no air present over there.

Atmosphere: It is a thick layer of air surrounding the earth’s surface is known as atmosphere.

Wind: The moving air is known as wind.

Air composition

→ Air contains mainly oxygen, nitrogen and remaining includes noble gases, carbon dioxide, water vapour, traces of other gases and dust particles.

→ Oxygen and nitrogen: air contains 28% oxygen and 78% nitrogen.

→ Oxygen helps in burning. It is used by living things to respire,

→ Nitrogen helps in growth of plant.

Carbon dioxide

→ Air contains 0.003% of carbon dioxide.

→ Carbon dioxide is also produced during burning.

→ Plants and animals produce carbon dioxide during respiration.

Water vapour

→ Air contains some amounts of water vapour depends upon the weather of a place.

→ Water vapour presence is very important for water cycle in nature.

Dust and Smoke

→ Smoke contains few gases with fine dust particles and is often harmful.

How does oxygen become available for all living beings?


→ They use carbon dioxide of the air to make their own food by a process called photosynthesis.

Aquatic animals

→ Most aquatic animals have special organs for respiration called gills. They use oxygen from air dissolved in water.


→ Some amphibians like frogs, salamanders need breathing systems for both water and air.

→ Frogs have lungs to breathe air when on land. In water, frogs breathe with their moist skin.


→ They have pair of lungs with air sacs which is open all the time, because birds need high level of oxygen during flight.


→ They breathe with the help of lungs. They take oxygen and give out carbon dioxide.

Properties of oxygen

→ Air is colourless

→ Air is transparent

→ It is essential for life

→ It occupies space

→ It present everywhere including water and soil

→ It exerts pressure
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