Be Equilibrium System if I will inject into the System O2(g) Radioactive.

Which of the materials in the System will be also a Radioactive after a while?

What are your thoughts? The answer seems so obvious that I wonder where you can possibly be confused.

Except N2 all the other materials in the System will be also a Radioactive after a while yes?

The oxygen added as a reagent is ALREADY radioactive. As it combines with nitrogen to form NO2, the product will be radioactive from the oxygen. Your answer with "After a while" causes me concern in that it is not obvious to me that you realize that the O2 is radioactive and, as it appears in other compounds, they will be radioactive too. As soon as they are formed. Then again, I might be wrong and you knew this already.