Process:  - Water comes into contact with something made of iron - The water combines with carbon dioxide in the air to form carbonic acid - As the acid is formed, the iron starts to dissolve - Some of the water breaks down into hydrogen and oxygen - The free oxygen and dissolved iron bond together - They form iron oxide, which is rust -   Perturbation hypothesis: suppose the iron is exposed to the air while wet happens, how will it affect MORE rust forming.  Does the supposed perturbation have an effect (direct or indirect) on the process?

yes