Let's say we have 2 Zinc atoms and 2 Sulfur atoms on one side of the equation. According to the Law of Conversation and Mass, how many Zinc Sulfide molecules would be on the other side of the equation?

Two

Explanation:

The law of conservation of mass states that in an isolated system the mass present is neither destroyed nor created by chemical changes or physical changes.

This tells us that the mass of reactants must be equal to the product mass.

If 1 atom of Zn react with one atoms of sulfur, the product will be 1 molecule of zinc sulfide according to the equation below

Zn (s) + S (s) ⇒ ZnS (s)

therefore two atoms each f zinc and sulfur will product two molecules of Zn sulfide