46. What is the name of the process by which nitrogen oxides and volatile organic compounds react in the presence of sunlight to form ozone?
a) Acidification
b) Reduction
c) Photochemical reaction
d) Oxidation
47. Which of the following is not a greenhouse gas?
a) Methane
b) Carbon dioxide
c) Nitrous oxide
d) Sulfur dioxide
48. What is the name of the atmospheric layer above the mesosphere?
a) Thermosphere
b) Stratosphere
c) Troposphere
d) Ionosphere
49. Which of the following is a common source of outdoor air pollution?
a) Cigarette smoke
b) Mold
c) Forest fires
d) Household cleaning products
50. Which of the following gases makes up the largest percentage of the Earth’s atmosphere by volume?
a) Nitrogen
b) Oxygen
c) Carbon dioxide
d) Argon
