[zacarais]

This is translated from a different language, so the nuances of the problem might be altered, but the essentially, the problem is this:

There are NO2, NO, and O2 in a chamber at STP. This chamber is open at the bottom and is situated at the surface of a tank of water. Assuming all the gases in the chamber completely react with the H2O to form HNO2, what is the possible range of concentration c of the resulting HNO2 if none of the product escapes? The correct answer is 1/39.2 < c < 1/28, but I do not know how these values were obtained.

Thanks for the help in advance. 

[Borek]

I don't see how to solve it without knowledge about relative amount of gases and water.