Question

Photochemical smog contains:
A. PAN
B. Ozone
C. Nitrogen dioxide
D. All of the above

Answer 1

Hint: Photochemical smog, which is often referred to as the summer smog, is the chemical reaction of sunlight, nitrogen oxides and volatile organic compounds that are present in the atmosphere, which leaves airborne particles harmful for the health and ground-level ozone. Photochemical smog depends on primary pollutants as well as the formation of secondary pollutants.

Complete step by step answer:

The photochemical smog is dependent on both the primary and secondary pollutants present in the atmosphere. The primary pollutants include nitrogen oxides, particularly nitric oxide ($$NO$$ ) and nitrogen dioxide ($$N{O}_2$$ ) and various other volatile organic compounds that get vaporized over a small range of temperature. The corresponding secondary pollutants of the photochemical smog include peroxyacyl nitrates (PAN), ozone present in the troposphere and aldehydes. An important secondary pollutant for photochemical smog is ozone, which is formed when hydrocarbons and nitrogen oxides ($$N{O}_x$$ ) combine in the presence of sunlight. The nitrogen dioxide ($$N{O}_2$$ ), which is formed as nitric oxide ($$NO$$ ), combines with oxygen ($$O_2$$ ) in the air. Also, in addition to this, when$$S{O}_2$$ and $$N{O}_x$$ are emitted, they are oxidized in the troposphere to nitric acid and sulfuric acid, which, when mixed with water, form the main components of acid rain. All of these harsh chemicals are usually highly reactive and oxidizing.
Thus, the correct option is D. All of the above.

Note:
Photochemical smog is considered to be a major problem of modern industrialization as it is the product of industrialization itself and requires to be controlled immediately before it is too late.. It is present in all modern cities, but it is more common in cities with sunny, warm, dry climates and a large number of motor vehicles. Because it travels with the wind, it can affect nearby sparsely populated areas as well and can cause various health risks.