2H2O2 ==> O2 + 2H2O ... balanced equation for decomposition of H2O2
moles O2 produced from 10.0 mole H2O2:
10.0 mol H2O2 x 1 mol O2 / 2 mol H2O2 = 5.00 moles O2
The volume of O2 is dependent on the temperature and pressure. Assuming STP, we have...
5.00 moles O2 x 22.4 L/mol = 112 L