Question

What is the percentage of oxygen in the atmosphere?
a)$78\%$
b)$21\%$
c)$12\%$
d)$11\%$

Answer 1

The Earth’s atmosphere consists of many different gases. These gases are present in various percentages. They are important to carry out various life processes. Some of the gases present in the atmosphere are in very small quantities and some of them are in majority.

Complete answer:
The atmosphere consists of many different types of gases. These gases are present in different quantities. The oxygen is present in $21\%$. It is the most important gas present in the atmosphere. It helps all the living organisms to breathe and continue their life. Oxygen is mainly produced by the plants and trees present on the Earth’s surface. The Earth’s oxygen level has been declining in the past few thousand years. This happened due to a decrease in the amount of the forest area and an increase in the industrialization and colonization. These two have affected the environment greatly and are affecting it to date. The air we inhale not only has oxygen in it but has a high amount of nitrogen present in it and also various other gases present in the atmosphere. The nitrogen gas is present in abundance in the atmosphere. It constitutes about $78\%$ of the total atmospheric air. Nitrogen is also essential as it helps the plants to grow and carry out their life process.

So, the correct answer is ‘ $21\%$ ’.

Note: The atmospheric air consists mainly of the nitrogen in the air. The second most abundant gas found in the atmosphere is oxygen. Various other gases like carbon dioxide, neon, and hydrogen are present in very minute quantities.