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2nd Class Science Our Environment Atmosphere


Category : 2nd Class

*   Introduction


The surrounding in which we live in is called our environment. Every living and non-living things is a part of our environment. In this chapter, we will study about the components of our environment.


*     Atmosphere

The simple meaning of atmosphere is the sphere of air. Air is the mixture of gases, therefore, atmosphere is also mixture of gases surrounding a celestial body. Although some details about the atmospheres of other planets and satellites are known, only the earth's atmosphere has been well studied. The science of detail study of the earth's atmosphere is called meteorology.


*      Atmosphere of the Earth

It is the layer of gases surrounding the earth. Atmosphere protects the life on the earth. Atmosphere has mass and it becomes thinner and thinner with increasing altitude. As atmosphere is the mixture of gases called air, therefore, atmosphere has the gases like nitrogen, oxygen, hydrogen, carbon dioxide, argon, helium and some more gases. Atmosphere has 78% nitrogen of total gases, 21% oxygen of total gases and remaining 1% is other gases. The remaining 1% is often referred as trace gases among which are the greenhouse gases like water vapor, methane, carbon dioxide, ozone. Oxygen is most important gas of atmosphere, because most of the living organism inhales this gas to be alive. Particularly human and animals inhale oxygen and exhale carbon dioxide, while plants inhale carbon dioxide and exhale oxygen.


Look at the picture of atmosphere around the earth given below:







    Atmosphere is the mixture of gases surrounding ______ body.

(a) Celestial

(b) Plastic

(c) Soil

(d) Ice


Answer: (a)


Atmosphere is the mixture of gases surrounding celestial body. Therefore, option (A) is correct and rest of the options is incorrect.



      Which one of the following gases is mostly available surrounding the earth?

(a) Nitrogen

(b) Oxygen

(c) Carbon dioxide

(d) Helium


Answers: (A)


Nitrogen gas in the atmosphere is 78 % of the total gases available in atmosphere. Therefore, option (A) is correct and rest of the options is incorrect.

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