Answer: Option (b) is the correct answer.
Explanation:
According to the law of conservation of mass, mass of a substance can neither be created nor it can be destroyed but it can simply be transformed from one form to another.
Therefore, when a metal is burned in a closed container, the mass of the container and its contents do not change because they follows law of conservation of mass.
Thus, we can conclude that when a metal is burned in a closed container, the mass of the container and its contents do not change then it is a law.
