Question

Which of the following quantities will always be the same before and after a chemical reaction?

The total number of neutrons of each element
The total mass of all substances
The total number of atoms of each element
The total mass of each substance
The total mass of each element
The total number of electrons of each element
The total number of molecules
The total number of neutrons
The total number of electrons
The total volume occupied by each element
The total number of protons
The total number of atoms
The total number of protons of each element
The total volume occupied by all substances

Answer 1

The total mass of all substances and the total number of atoms of each element will always be the same before and after a chemical reaction, this is based on the Law of Conservation of Mass and the Law of Conservation of atoms. This law states that in any chemical reaction, the total mass of the reactants is equal to the total mass of the products and the number of atoms of each element is conserved.