Question

Smog clouds of sulphur dioxide, water droplets and sulphuric acid droplets can be referred to as _______.

• A. Photochemical smog
• B. Oxidising smog
• C. Los Angles smog
• D. Reducing smog

Hint:

Sulphur dioxide is a reducing agent. This is classical (London) smog.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
There are two main types of smog. Classical smog (London type) comes from coal smoke, sulphur dioxide and fog. Photochemical smog (Los Angeles type) comes from vehicle exhaust and sunlight.

Step 2: Key Approach:
Match the ingredients named in the question, sulphur dioxide, water droplets and sulphuric acid, with one of the two types.

Step 3: Detailed Explanation:
Sulphur dioxide and sulphuric acid with water vapour are the signs of classical smog. Sulphur dioxide is a reducing agent, so classical smog is also called reducing smog.

Step 4: Check option (1).
Photochemical smog contains ozone, PAN and aldehydes, not sulphuric acid mist. So (1) is wrong.

Step 5: Check option (2).
Oxidising smog is another name for photochemical smog, because ozone and PAN are strong oxidisers. So (2) is wrong.

Step 6: Check option (3).
Los Angeles smog is the photochemical type. So (3) is wrong.

Step 7: Check option (4).
Reducing smog is the classical type made of sulphur dioxide, droplets and sulphuric acid. So (4) is right.

Final Answer:
The smog described is reducing smog, option 4.
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