The increase in the mass of the nail from 50 grams to 55 grams due to rusting can be explained by the principles of chemistry and conservation of mass. When the iron nail rusts, it reacts with oxygen in the air and moisture (water) to form iron oxide, commonly known as rust (Fe₂O₃·nH₂O).
During this process, the nail absorbs oxygen from the environment, and if moisture is present, it may also absorb water. The additional mass observed (5 grams in this case) comes from the oxygen molecules that combine with the iron in the nail to create rust.
Overall, the law of conservation of mass states that mass in an isolated system cannot be created or destroyed; it can only change forms. In this scenario, the mass from the surrounding environment (oxygen and possibly water) becomes part of the nail's mass as it transforms into rust. Thus, even though the nail's mass has increased, this does not violate the conservation of mass; instead, it reflects that the nail has undergone a chemical change that involved the absorption of matter from outside.