Cu+SO2= Cu2S+O2

Why isnt the answer Cu2SO2 why is it Cu2S+O2

3 answers

How do i know when there are separate compounds and not 1 answer with all chemicals bonded
Where is this coming from? It is not balanced as written. Seems more likely that
Cu2S + O2 ---> 2 Cu + SO2 (stinky stuff) ?????
Cu2S + Cu2S = SO3 + Cu