The balanced chemical reaction would be as follows:
2H2O2 = 2H2O + O2
We are given the amount of the peroxide that decomposes. Using this as the starting point for the calculations, we can determine the amount of O2 produced. We do as follows:
14.3 mol H2O2 ( 1 mol O2 / 2 mol H2O2 ) = 7.15 mol O2 produced