Copper(I) sulfide (Cu2S) is synthesized in a reaction described by this chemical equation: 2Cu(s) + S(s) → Cu2S(s)

A ratio of 2:1 applies to the that enter into the reaction.

a. volumes of gases

b. number of molecules

c. number of atoms

d. masses of the reactants

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Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.