The ozone layer in the Earth's stratosphere has an average total pressure of 10 mm Hg 11.3 * 10-2 atm2. The partial pressure of ozone in the layer is about 1.2 * 10-6 mm Hg 11.6 * 10-9 atm2. What is the concentration of ozone in parts per million, assuming that the average molar mass of air is 29 g/mol?