Question

What is the percentage of oxygen in the air?

• A. 20.9 %
• B. 79 %
• C. 10 %
• D. 0.33 %

Answer 1

The correct option is A

20.9 %

Explanation for the correct option

A. Oxygen - 20.9%

• It is the amount of oxygen present in atmosphere.
• Atmosphere is blanket of many gases which envelope the planet i.e earth.
• Atmosphere is divided into 5 major layers: a) Troposphere b) Stratosphere c) Mesosphere d) Thermosphere e) Exosphere
• Various gases present in atmosphere are -

• Nitrogen (N₂) = 78.1%
• Oxygen (O₂) = 20.9%
• Argon (Ar) = 0.1%
• Carbon dioxide = 0.04%
• Other gases (Hydrogen , Neon, Helium, Methane etc.) = 0.85%

Explanation for the incorrect option

B. 79% (approximately) - It is the amount of Nitrogen (N₂) present in atmosphere.

C. 10% - No such gas has composition of 10% in atmosphere.

C. 0.33% - No such gas has composition of 10% in atmosphere.

Hence, Option (a) is correct, 20.9% is the amount of oxygen present in atmosphere.