Question

Which of the following group of gases cause photochemical smog?

• A. O${}_3$, PAN and CO
• B. HC, NO and PAN
• C. O${}_2$, PAN and NO${}_2$
• D. O${}_3$, PAN and NO${}_2$

Answer 1

The correct option is D O${}_3$, PAN and NO${}_2$

The photochemical smog can act as a pollution indicator. It is formed by the action of solar radiation with airborne pollutants like nitrogen oxides and volatile organic compounds. Primary pollutants are often introduced into the atmosphere through automobile emissions and industrial processes. Ultraviolet light can split nitrogen dioxide into nitric oxide and monatomic oxygen; this monatomic oxygen can then react with oxygen gas to form ozone. Products like ozone, aldehydes, and peroxyacetyl nitrates are called as secondary pollutants. The mixture of these primary and secondary pollutants forms photochemical smog. Thus, the correct answer is option D.