Question

an iron nail is taken to the moon. Another is kept near the gateway of india. And the third oneis kept near red fort compare the degree of rust formaion on the 3 nails

Answer 1

Rust is form by the chemical reaction of iron with oxygen in presence of water.
4Fe + 2H₂O + 3O₂ -> 4FeO(OH) or
the hydrated molecule is also written as Fe₂O₃ .nH₂O
Rusting is accelerated in the presence of acids or any electrolyte.

Since there is no oxygen on moon so there will be no rusting of iron on moon.
Delhi is more polluted as compared to Mumbai and it has higher concentration of oxides of sulphur and nitrogen as pollutants in air to produce acids. So the degree of rust formation will be higher near Red fort than Gateway of India.