Question

Tick the correct answer
Major constituent of the atmosphere by percent is
a)Nitrogen
b)Oxygen
c)Carbon Dioxide
d)None of these

Answer 1

Hint:Atmosphere is the layers of air that cover the earth. Earth's atmosphere is about 300 miles (480 kilometers) thick, but most of it is within 10 miles (16 km) the surface. It is made of gases , water vapour and dust particles. The layer of air surrounding the earth is further divided into troposphere, stratosphere, mesosphere, thermosphere and exosphere. This categorization is done based on temperature conditions.

Complete Answer:The atmosphere consists of gases,water vapour and dust. The amount of these components keep on changing with altitude.
Water vapour and dust particles decrease in quantity with increase in altitude.
Earth’s atmosphere has a number of gases in it and to attempt this question let us look at the options given to us.

Option (a) nitrogen makes up 78% of the atmosphere. The nitrogen in the atmosphere is mostly unreactive but it is turned into nitrates and nitrites which are essential for plants.

Option (b) oxygen makes up 20% of the atmosphere and is essential for humans to survive.

Option (C ) carbon dioxide 0.036% of atmosphere. But it is an essential gas as it absorbs a part of terrestrial radiation maintaining the heat of the planet. However due to increasing carbon dioxide in the atmosphere , the temperature of the earth is increasing causing climate change .

Therefore the correct answer is (A)-Nitrogen.

Note:The atmosphere has other gases like argon, helium, neon, xenon etc. After oxygen, it is argon that is the third highest in percentage in the atmosphere
It is also important to note that the earth’s atmosphere has changed over the years. 4.6 billion years ago, earth’s atmosphere only had nitrogen and carbon dioxide ,with no trace of oxygen. It was only around 2billion years ago, when photosynthesizing bacteria developed, oxygen was released.