The main constituents of atmospheric air are Oxygen (O₂) and Nitrogen (N₂). The composition of O₂ and N₂ is approximately :
29% and 70% respectively.
19% and 80% respectively.
21% and 78% respectively.
23% and 76% respectively.
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC CISF-AC-EXE – 2022
The approximate composition of dry atmospheric air by volume is:
Nitrogen (N₂) ≈ 78.09%
Oxygen (O₂) ≈ 20.95%
Argon (Ar) ≈ 0.93%
Carbon Dioxide (CO₂) ≈ 0.04%
Trace gases (Neon, Helium, Methane, Krypton, Hydrogen, etc.) make up the rest. Water vapor is also present, but its concentration varies significantly depending on location and weather. The question likely refers to dry air composition.
Looking at the options for the composition of O₂ and N₂:
A) 29% O₂, 70% N₂
B) 19% O₂, 80% N₂
C) 21% O₂, 78% N₂
D) 23% O₂, 76% N₂
Comparing these options to the actual percentages (≈20.95% O₂ and ≈78.09% N₂), option C (21% and 78%) is the closest approximation.
– The main constituents are Nitrogen (N₂) and Oxygen (O₂).
– Their approximate percentages by volume are about 78% Nitrogen and 21% Oxygen.