Question

Correct statement about smog is

• A. NO₂ is present in classical smog
• B. Classical smog also has high concentration of oxidizing agents
• C. Photochemical smog has high concentration of oxidizing agents
• D. Both NO₂ and SO₂ are present in classical smog

Hint:

To differentiate between classical and photochemical smog:
• Classical smog occurs in cool, humid conditions and is reducing in nature.
• Photochemical smog occurs in sunny conditions and contains strong oxidizing agents like ozone.

Answer 1

The Correct Option is C

To solve this question, we need to understand the types of smog and their chemical composition.

Types of Smog

There are mainly two types of smog:

1. Classical Smog: It is also known as London smog or sulfurous smog. It typically occurs in a cool, humid climate and is formed due to the use of coal, which releases smoke and sulfur dioxide (SO_2) when burned. It does not contain oxidizing agents.
2. Photochemical Smog: Also known as Los Angeles smog, it occurs in warm, sunny conditions. It is formed when sunlight reacts with industrial pollutants such as nitrogen oxides (NO_x) and volatile organic compounds (VOCs). This type of smog contains high concentrations of oxidizing agents such as ozone (O_3).

Analysis of the Options

• Option 1: "NO₂ is present in classical smog" - This is incorrect. Classical smog primarily involves sulfur dioxide (SO_2) rather than nitrogen dioxide (NO_2).
• Option 2: "Classical smog also has a high concentration of oxidizing agents" - Incorrect. Classical smog does not have oxidizing agents; it primarily consists of reducing agents like SO_2.
• Option 3: "Photochemical smog has a high concentration of oxidizing agents" - This is correct. Photochemical smog is characterized by the presence of oxidizing agents such as ozone.
• Option 4: "Both NO₂ and SO₂ are present in classical smog" - Incorrect. While SO_2 is present, NO_2 is not typically associated with classical smog.

Conclusion

The correct statement is that "Photochemical smog has high concentration of oxidizing agents," which aligns with the chemical processes involved in photochemical smog formation.