How long would it take a 2.5 micron particle with a density of 2.2 g/cm to fall 100 m in a sea level atmosphere? Assume the air temperature is 20C. 150 days 151 days 152 days 153 days 154 days 155 days 156 days 157 days 158 days 159 days 160 days QUESTION 3 For the street sellers in problem 2, assume that they live and work downtown so that they are exposed 24/7 for a year. What concentration of CO would cause % COHb to reach 10%. 60 ppm 61 ppm 62 ppm 63 ppm 64 ppm 65 ppm 66 ppm 67 ppm 68 ppm 69 ppm 70 ppm