Explanation:
The given reaction is as follows.
[tex]2Cu(s) + S(s) \rightarrow Cu_{2}S(s)[/tex]
In this reaction, there are 2 atoms of copper and one atom of sulfur are reacting with each other and result in the formation of copper(I) sulfide.
Therefore, we can conclude that there is a ratio of 2:1 applies to the number of reactant atoms that enter into the reaction.
