For the combustion reaction: C₈H₁₈ + 12.5 O₂ + 47 N₂ 8 CO₂ + 9 H₂O + 47 N₂ . If 0.2% (or 0.002 mole of fuel is unburned in the form of VOC, the concentration of VOC in the exhaust prior to the catalytic converter is _______ ppm. (Hints: the mole ratio of a gas mixture is the same as the volume ratio).