Question

An equation that has the same amount of atoms of each element on both sides of the reaction obeys what law?

A. Law of conversation of energy
B. Law of conversation of mass
C. Law of conversation of atoms
D. Law of conversation of temperature

Answer 1

I beieve that it is either B or C, I was never good in chemistry. 

Answer 2

B. Law of conversation of mass

According to that law, mass remains constant and cannot be either created or destroyed

Hope this helps!