Which gas makes up the largest proportion of the air that we breathe?

• A. Nitrogen (N_2)
• B. Carbon dioxide (CO_2)
• C. Oxygen (O_2)
• D. Argon (Ar)

Answer: (A)

Verified step by step guidance

1. Understand that air is a mixture of different gases, each present in varying proportions by volume.
2. Recall the major components of dry air and their approximate volume percentages: Nitrogen (N\_2) about 78%, Oxygen (O\_2) about 21%, Argon (Ar) about 0.93%, and Carbon dioxide (CO\_2) about 0.04%.
3. Compare these percentages to determine which gas has the highest proportion in the air.
4. Recognize that Nitrogen (N\_2) has the largest volume percentage among the gases listed.
5. Conclude that Nitrogen (N\_2) is the gas that makes up the largest proportion of the air we breathe.