What is the third most common gas found in the air we breathe ________ ?

A. Hydrogen
B. Neon
C. Carbondioxide
D. Argon

 
The most common gas people breathe from clean air is nitrogen. Air is a mixture of gases, and the air on Earth contains about 78 percent nitrogen and about 21 percent oxygen. Argon, carbon dioxide neon, helium, methane, krypton, hydrogen and xenon are in much smaller amounts.