Answer: The reaction does occur.
Explanation: For the reaction of aqueous strontium sulfide and aqueous copper(II) sulfate, the reaction follows:

This reaction is a type of precipitation reaction.
The precipitate formed is CuS which is black in color.
I think It means that any balanced equation is conserved. Meaning that the equation is equal. The law states matter can’t be created or destroyed. In chemical reactions the mass of an element is the same before and after the product. There’s two sides two an equation the reactants side and the product’s side. Hope this helps.
Ca(OH)2 (aq) because of elements oxygen and hydrogen
Ca(OH)2(aq)+H2SO4(aq)—→ CaSO4(s)+ 2H2O(l)