Answer the following question given this paragraph: 

A: All chemical equations must be balanced. This means that there must be the same number of each type of atom on both sides of the arrow. That’s because mass is always conserved in chemical reactions. Count the number of hydrogen and oxygen atoms on each side of the arrow. There are two hydrogen atoms in both reactants and products. There are two oxygen atoms in the reactants but only one in the product. Therefore, equation 1 is not balanced.


Q: What is always conserved in chemical reactions?

 Choices:

- energy

- bonds

- force

- mass

A:
mass
