Question

By volume about __________ of air is nitrogen and about __________is oxygen.

• A. 78%
• B. 21%

Answer 1

Air:

• Air is the homogeneous mixture of different gases.
• Air is mainly composed of nitrogen (${\mathrm{N}}_2$) 78%, oxygen(${\mathrm{O}}_2$) 21%, carbon dioxide(${\mathrm{CO}}_2$) 0.03%, and other gases 1%.
• Nitrogen is the most abundant gas in the atmosphere.

Therefore, By volume about 78% of air is nitrogen, and about 21%is oxygen.