In this lesson we are going to learn all the interesting facts about atmospheric contents, i.e. contents which are always present around us. How those materials helps us in some aspects and many more things. So let’s start our discussion with some basic questions.

1) What happens when we breathe?

2) What exactly we take in and out while breathing?

3) What atmosphere is consisting of?

So children’s, answers of these all question relates us with concept of “AIR”.


We all know that our planet i.e. earth is covered by very thick and large layer called Atmosphere. The atmosphere of earth is made up of different gases. All these gases are present in different quantities as a mixture. This mixture of gases which is present around us is termed as AIR. Air helps us to survive, because the main content from this mixture is oxygen, carbon di-oxide, which are most essential for our life,that is why Oxygen is known as life line of animals, which is nothing but part of air. Following are the main gases present in atmosphere with their amount in percentage.

  1. Nitrogen- 78%
  2. Oxygen- 21%
  3. Carbon dioxide & other gases 01%

Air - Class 7

Along with CO2 other gases includes hydrogen, neon etc.

You must have seen that smoke always goes up. What should be logic behind this?

Remember that, air depends upon several factors like pressure, temperature and volume (space occupied). These three factors are correlated with each other.

Just observe your mother while she cooks a delicious ‘Pulaw’ for you. You must have seen her putting all ingredients in a pressure cooker. Why she doesn’t use a simple pot like Kadhai?

Here the term pressure is very crucial to cook those ingredients as early as possible. For this we need to increase the pressure, so we provide constant heat (temperature).

From above discussion we can conclude that, if temperature of air changes, its pressure also changes, these characteristics of air plays very vital role in most of natural phenomena.

Warmer air occupies more space hence it becomes lighter than that of cold air, which can occupy in small space too.

Just try: Take two balloons of same size, blow it with air and heat them. What will happen? Observe carefully without getting harmed to yourself.

Q. What do you mean by air?

Ans: The mixture of all gases present in the atmosphere is known as Air.

Q. Which gases do we need for respiration?

Ans: Oxygen, and Carbon dioxide.

Q. Which gas is called as life line for animals?

Ans: Oxygen.

Q. Which gas is present in maximum extent in air?

Ans: Nitrogen-78 %

Q. What happens to air when its temperature increases?

Ans: When temperature of air gets increased, its flows upwards.

Updated: April 4, 2021 — 12:28 pm

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