Question

Modern coal-based thermal power stations pollute the atmosphere by adding:

• A. NOX and SO2
• B. NOX, SO2 and SPM
• C. NOX, SO2, SPM and CO
• D. NOX, SO2 and CO

Hint:

Coal combustion mainly contributes to gaseous pollutants like NOX and SO2, along with particulate pollution in the form of ash and dust.

Answer 1

The Correct Option is B

Step 1: Understanding coal-based thermal power stations.
Coal-based thermal power stations generate electricity by burning coal. During combustion, various pollutants are released into the atmosphere due to the presence of impurities in coal and incomplete combustion processes.
Step 2: Identifying major pollutants released.
Burning coal releases nitrogen oxides (NOX) due to high-temperature combustion, sulphur dioxide (SO2) because coal contains sulphur impurities, and suspended particulate matter (SPM) in the form of ash and fine dust particles.
Step 3: Analyzing the options.
(A) NOX and SO2: Incorrect, as this option ignores particulate matter, which is a major pollutant.
(B) NOX, SO2 and SPM: Correct, as modern coal-based thermal power stations mainly emit these three pollutants.
(C) NOX, SO2, SPM and CO: Incorrect, as carbon monoxide (CO) is not a significant emission in modern thermal power plants due to efficient combustion.
(D) NOX, SO2 and CO: Incorrect, since it excludes suspended particulate matter.
Step 4: Conclusion.
The correct answer is (B) NOX, SO2 and SPM because these are the primary atmospheric pollutants released by modern coal-based thermal power stations.

Answer 2

Coal contains impurities such as sulfur, and its combustion at high temperatures in a power station produces several distinct byproducts. Let's check what each option includes or leaves out:

1. NOx and SO2: Nitrogen oxides form from high-temperature combustion of air, and sulfur dioxide forms from sulfur impurities in coal, both are genuine emissions, but this option leaves out the fine ash and dust particles that coal combustion also releases in large quantities.
2. NOx, SO2 and SPM: Along with the gases above, burning coal also produces suspended particulate matter (SPM), fine ash and soot carried into the air. These three together are recognized as the primary pollutants of coal-based thermal power stations.
3. NOx, SO2, SPM and CO: Carbon monoxide forms mainly from incomplete combustion; modern thermal stations are designed for efficient, largely complete combustion, so CO is not considered one of their characteristic major pollutants.
4. NOx, SO2 and CO: This drops particulate matter, which is one of the most visible and significant pollutants from coal burning, so leaving it out understates the actual pollution profile.

The set that captures the actual major pollutants, without omitting particulate matter or wrongly including CO, is the three-pollutant option.

Therefore, the correct answer is NOx, SO2 and SPM.