The normal level of carbon dioxide in the atmosphere is
A
78%
B
10%
C
0.03%
D
15%
Correct Option:
C
Explanation
0.03% is the traditional school-textbook value for the proportion of carbon dioxide in atmospheric air and is therefore the intended answer in this older paper. Atmospheric CO₂ concentrations have increased, so modern values are somewhat above this old approximation. The key exam concept is that CO₂ constitutes only a small fraction of one percent of the atmosphere, unlike nitrogen or oxygen.
