Question

Can anyone tell me all the constituents of air and their percentage?

Answer 1

The atmosphere is composed of a mix of several different gases in differing amounts.  The permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon.  Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%.  Gases like carbon dioxide, nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the atmosphere.  Water vapor is unique in that its concentration varies from 0-4% of the atmosphere depending on where you are and what time of the day it is.  In the cold, dry artic regions water vapor usually accounts for less than 1% of the atmosphere, while in humid, tropical regions water vapor can account for almost 4% of the atmosphere.  Water vapor content is very important in predicting weather.

Answer 2

here is the composition of air:

Nitrogen-78%

oxygen-20.9%

argon-0.93%

carbon dioxide-0.03%

the other gases like neon , methane, krypton, helium etc are present in negligible amount.