Question

Which of the following pollutants are matched correctly with their effects?

1. Sulphur oxides – Destruction of chlorophyll

2. Nitrogen oxides – Formation of ozone in photochemical smog

3. Methane – Causes lung cancer

4. Carbon monoxide – Respiratory blockage due to haemoglobin binding

• A. 1, 2 and 4
• B. 2, 3 and 4
• C. 1 and 3 only
• D. All are correct

Answer 1

Answer:

A. 1, 2 and 4

• Correct Answer: Option A) 1, 2 and 4

• Sulphur oxides – Destruction of chlorophyll. This is correct. Sulphur dioxide (SO₂) and other sulphur oxides are known to damage plant tissues and cause chlorosis (yellowing of leaves) by destroying chlorophyll.

• Nitrogen oxides – Formation of ozone in photochemical smog ✓

• This is correct. Nitrogen oxides (NOₓ) react with volatile organic compounds in the presence of sunlight to form ground-level ozone, which is a major component of photochemical smog.

• Methane – Causes lung cancer. This is incorrect. Methane (CH₄) is primarily a greenhouse gas that contributes to climate change. It is not classified as a carcinogen and does not directly cause lung cancer. Methane can be an asphyxiant at very high concentrations, but its primary health concerns are related to its explosive properties, not cancer.

• Carbon monoxide – Respiratory blockage due to haemoglobin binding. This is correct. Carbon monoxide (CO) binds to hemoglobin in the blood with an affinity approximately 250 times greater than oxygen, forming carboxyhemoglobin. This prevents oxygen transport in the blood, leading to hypoxia and respiratory problems.