Nitrogen oxides, NOx, play an essential role in the production of pollutants found in photochemical smog. The NOx in the atmosphere is slowly broken down to N2 and O2 in a first order reaction. The average half-life of NOx in the smokestack emissions in a large city during daylight hours is 3.9 hours. A. Starting with 1.50mg in an experiment, what quantity of NOx remains after 5.25 hours. B. How many hours of daylight must have elapsed to decrease 1.50mg of NOx to 2.50 to 10^-6 mg?