Question

Choose the INCORRECT statement:

• A. Photochemical smog is formed more in winter season compared to summer season.
• B. Tropospheric Ozone is a constituent of photochemical smog
• C. Stratospheric Ozone protects us from harmful UV-B radiations
• D. Tropospheric Ozone is referred as Bad Ozone

Hint:

"Photochemical" = Photo (Light) + Chemical. It needs strong sun. If a question mentions "smog" and "winter," it usually refers to sulfurous smog, not photochemical smog.

Answer 1

The Correct Option is A

Concept: Photochemical smog is a type of air pollution derived from vehicle emissions from internal combustion engines and industrial fumes. These pollutants react in the atmosphere with sunlight to form secondary pollutants.

Step 1: Understanding Photochemical Smog.
Photochemical smog requires high-intensity solar radiation (sunlight) to trigger the chemical reactions between nitrogen oxides ($NO_x$) and volatile organic compounds (VOCs). Consequently, it is a characteristic of summer or warm, sunny days rather than winter. Traditional "London-type" smog (sulfurous smog) is what typically occurs in cold, damp winter conditions. Therefore, statement (1) is incorrect.

Step 2: Evaluating Ozone statements.
Ozone is "good" in the stratosphere because it blocks UV rays but "bad" in the troposphere because it is a toxic pollutant and a major component of photochemical smog. Statements (2), (3), and (4) are all scientifically correct.