If calcium carbonate (caco3) decomposes, what would the product of the reaction be?

It was C) CaO on edg

The balanced equation is expressed:

H2S + 3/2O2 --> SO2 + H2O 

We are given the amount of O2 to be used in the reaction. This will be the starting point for our calculations. We do as follows:

6 mol O2 ( 1 mol SO2 / 3/2 mol O2 ) = 4 moles SO2 produced

Hope this answers the question. Have a nice day.