How many moles of ethylene (C2H4) can react with 12.9 liters of oxygen gas at 1.2 atmospheres and 297 Kelvin? C2H4(g) + 3O2(g) yields 2CO2(g) + 2H2O(g) 0.21 moles 0.32 moles 0.63 moles 0.84 moles