What gases are found in fresh air?

Question

This is a science question from my kid's science class. The gases given are Oxygen, Carbon Dioxide, Nitrogen and Water Vapour. I think fresh air should contain all of them, since air is made of these gases and what is so special about fresh air.

Answer 1

It smells good . The CO2 is a very heavy gas and is right on the ground.

Answer 2

All air contains those things, with little variation (except maybe water vapor).  What we notice about fresh air might be a few things:

In a city, air that contains pollutants like exhaust gases (incompletely burned hydrocarbons, nitrous oxides, sulfur compunds) will not seem fresh.

In a crowded room (esp. a long time), air will not seem fresh because of building levels of CO2 from the people's exhalations, and we must work harder (breathe faster) to eliminate CO2 from our own body.

Outdoors, we can smell certain things in the air that are pleasant to us and make it seem fresher - near the sea we can smell the sharp negative ions from salt spray, in meadows there are traces of flower scent; forests cansmell piney, etc.

Answer 3

All of them

if you are talking about which gas has a higher precence in fresh air it would be Nitrogen.  

Like is said above polluted air may have a higher carbon dioxide rate - but would still only be in the low %

so the question is faulty or it is a trick (like an all of the above question)

Answer 4

Air Composition

The sea-level composition of air (in percent by volume at the temperature of 15°C and the pressure of 101325 Pa) is given below.

Nitrogen 78.084 %

Oxygen 20.9476 %

Argon 0.934 %

Carbon Dioxide 0.0314 %

Neon 0.001818 %

Methane 0.0002 %

Helium 0.000524 %

Krypton 0.000114 %

Hydrogen 0.00005 %

Xenon 0.0000087 %