Question

Which of the following is a secondary pollutant ?

• A. CO
• B. SO₂
• C. CO₂
• D. O₃

Answer 1

The Correct Option is D

To determine which option is a secondary pollutant, we need to understand the difference between primary and secondary pollutants:

1. Primary Pollutants: These are pollutants that are directly emitted into the atmosphere from sources. Examples include carbon monoxide (CO), sulfur dioxide (SO₂), and carbon dioxide (CO₂).
2. Secondary Pollutants: These are not emitted directly. Instead, they form in the atmosphere through chemical reactions between primary pollutants and other components in the atmosphere. Ozone (O₃) is a typical example of a secondary pollutant that forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight.

Given the options:

• CO (Carbon Monoxide): A primary pollutant emitted from vehicle exhaust, industrial processes, etc.
• SO₂ (Sulfur Dioxide): A primary pollutant that comes from fossil fuel combustion at power plants and other industrial settings.
• CO₂ (Carbon Dioxide): A primary pollutant released from burning fossil fuels, among other sources.
• O₃ (Ozone): A secondary pollutant formed by the reaction of sunlight with primary pollutants like NOx and VOCs.

Therefore, the correct answer is:

O₃ (Ozone) - It is a secondary pollutant.