Question

'Smog', which means 'smoke' plus 'fog', irritates eyes and the throat. Smog is mainly caused by pollutants from automobiles and industries when they:
A.Hit a dense shower of snow flakes
B.React photochemically, due to the effect of ultraviolet light
C.Form a smoke ring
D.React with oxygen in the air due to lightning electrical discharge from clouds

Answer 1

We know that smog is a type of air pollution. Smoke is nothing but a combination of smoke and fog present in the air. We have that smog is a problem in several cities and continues to affect human health. It is formed when pollutants are liberated to the air.

Complete answer:
We can say that classical smog comes from huge amounts of burning of coal and it is caused by a mixture of sulfur dioxide and smoke. Smog includes several chemicals such as nitrogen oxide, sulfur dioxide, carbon monoxide, and volatile organic compounds. The two major components of smog are ground level ozone $\left( {{O_3}} \right)$ and particulate matter.
Smog is of two type’s normal smog and photochemical smog.
Normal smog happens due to burning of huge amounts of high sulfur coal.
Photochemical smog happens when ultraviolet light from the sun comes in contact with nitrogen oxides present in the atmosphere. It is mainly caused because of the pollutants that are released from industries and automobiles. Nitrogen oxide that is produced in engines of cars when released into the atmosphere they react with water to form nitric acid (or) they react with oxygen to form a single molecule of oxygen, which later combines with molecule oxygen to form ozone. The nitric acid gets precipitated into air as acid rain. Because of the direct production of nitrogen oxide by vehicles, the formation of smog over cities and causes adverse health effects.
Therefore, option (B) is correct.

Note:
We have to remember that some of the photochemical oxidants are $N{O_2}$, ozone, and PANs. They react and oxidize certain compounds present in the atmosphere (or) inside lungs of a person, which are oxidized. Small amounts of these chemicals affect the respiratory tract of animals and humans. It damages trees and crops.