The law of conservation of mass is shown by option A as the number of atoms on the left and right are exactly balanced.
What is the law of conservation of mass?
The law of conservation of mass, which states that the total mass of the constituents in a closed system before a chemical reaction is equal to the total mass of the constituents after the reaction, is a fundamental concept in chemistry. Stated differently, mass is neither created nor destroyed during a chemical reaction; rather, it is conserved.
This principle is based on the idea that, instead of being created or destroyed, atoms are rearranged to form new compounds during a chemical reaction.