Question

The percentage of $CO_2$ in atmosphere is
A. 7.8%
B. 0.03%
C. 0.04%
D. 0.01%

Answer 1

Hint: Atmosphere comprises various layers and gases that surround a particular planet. These layers and gases most often have important roles in shaping the overall environment and life forms on the particular plant.

Complete Answer:
- The most important role of the atmosphere is that it helps to protect genetic damage in living organisms from solar ultraviolet radiation, solar wind and cosmic radiation. The atmosphere of the Earth comprises various gases which differ in the amounts they are present in.
- The gases include nitrogen which comprises 78%, oxygen which comprises about 21%, argon about 0.9%, carbon dioxide about 0.03% and few other gases which are present in trace amounts.
- Each of these gases plays different roles such as the nitrogen present in the atmosphere is fixed by certain bacteria and lightning which converts it into ammonia. This ammonia is then used in the formation of nucleotides and amino acids.
- The oxygen present in the atmosphere is used for respiration by all aerobic organisms. The carbon dioxide is used by green plants, certain species of algae and bacteria for the process of photosynthesis.

So the correct option is B) 0.03%.

Note: Each of the gases in the atmosphere play vital roles. They should be maintained at the appropriate amounts, failure of which can have damaging effects on the environments and also on the organisms. The current scenario of global warming is due to a disbalance in the concentration of these gases.