Answer :
This is a type of chemical reaction in which an iron nail react with water and oxygen to give iron oxide as a product. This process is known as rusting of iron.
Rusting of iron is an oxidation-reduction reaction in which iron losses electrons to oxygen atom.
The balanced chemical reaction for rusting of irons is,
The mass of iron = 56 g
The mass iron oxide = 140 g
From this we conclude that, the mass of iron oxide has more mass than the original mass of iron. That means the mass of the object after rusting is increases when compared with its original mass.