The proportion of carbon dioxide in the atmosphere is about _______ .
0.03%
0.93%
78.09%
0.10%
The proportion of carbon dioxide in the atmosphere is about 0.03%
About a hundred years ago, the proportion of carbon dioxide in air was about 0.029%. Today it is 0.035%. What is the reason?
The proportion of oxygen and carbon dioxide in the atmosphere is maintained by ___ .
Carbon dioxide is a part of our atmosphere.