Instructions: Choose One Answer from Each Pair of Selections

Q18: On clear, cold winter nights, cities tend

Q19: Instructions: Choose one answer from each pair

Q20: Photochemical smog _.<br>A) only forms at night<br>B)

Q21: Which substance is considered a primary pollutant?<br>A)

Q22: Which gas is a major source of

Q24: Which pollutant is formed during the incomplete

Q25: Instructions: Choose one answer from each pair

Q26: In which area would air pollution typically

Q27: Explain how the semipermanent Pacific high off

Q28: Where was the term smog first used,