Question:

Point out the true statement. Photochemical smog occurs in a daytime while the classical smog occur in the morning hours. Classical smog has an oxidising character whereas the photochemical smog is reducing in character. During formation of smog, the level of ozone in the atmosphere goes down. Classical smog is good for health but not photochemical smog.

Photochemical smog occurs in a daytime while the classical smog occur in the morning hours

During formation of smog, the level of ozone in the atmosphere goes down

Classical smog is good for health but not photochemical smog

Classical smog has an oxidising character whereas the photochemical smog is reducing in character

Solution:

The correct option is A. Photochemical smog occurs in a daytime while the classical smog occur in the morning hours. London-type smog or classical smog is caused mainly by air pollution due to combustion of coal and emission of sulphur dioxide and dust. Its formed in the morning of winter season especially. Photochemical smog or los vegas smog is a type of air pollution produced when sunlight acts upon motor vehicle exhaust gases to form harmful substances. Its formed during mid day especially. Hence option A is correct.