Question

Oxygen concentration in Earth's atmosphere is roughly?

• A. 18%
• B. 21%
• C. 24%
• D. 28%

Answer 1

Answer:

B. 21%

• The Earth's atmosphere is a mixture of gases, primarily consisting of Nitrogen (N₂) and Oxygen (O₂).

• Nitrogen constitutes approximately 78.08% of the atmosphere by volume.

• Oxygen (O₂) makes up approximately 20.95%, which is conventionally rounded to 21% for most competitive examination purposes.