Previous Year Question
Which one of the following is not correctly matched?
Green House Gas — Source
Carbon dioxide — Thermal Power Stations
Chloro fluro carbon — Automobile
Nitrous Oxide — Waterlogged Paddy fields
Sulphur dioxide — Brick Kilns
Correct Answer: B
Detailed Solution
Greenhouse Gases are atmospheric gases that produce the Greenhouse Effect by absorbing and re-emitting Infrared Radiation emitted from the Earth's surface. Major examples include Carbon Dioxide (CO₂), Methane (CH₄), Nitrous Oxide (N₂O), and Chlorofluorocarbons (CFCs). The pairing Carbon Dioxide — Thermal Power Stations is correct because the combustion of coal and other fossil fuels releases substantial amounts of CO₂.
Chlorofluorocarbons (CFCs) are synthetic chemical compounds containing carbon, chlorine, and fluorine. Historically, they were used in refrigerators, air conditioners, Aerosol Propellants, and foam manufacturing. Combustion in conventional automobile engines produces CO₂, Carbon Monoxide (CO), Nitrogen Oxides (NOₓ), and other pollutants, but not CFCs. On this basis, examination solutions generally treat the Chlorofluorocarbon–Automobile pairing as mismatched. However, CFC-12 was used in older automobile air-conditioning systems, so automobiles cannot be regarded as an entirely impossible source of CFC emissions.
Nitrous Oxide (N₂O) is a potent Greenhouse Gas released through microbial Nitrification and Denitrification processes in agricultural soils. Flooded paddy fields primarily emit Methane (CH₄) because waterlogging produces oxygen-deficient, Anaerobic Conditions in the soil. However, rice cultivation can also release N₂O, particularly through nitrogen fertilizer application and alternating flooding and drainage. Therefore, the association between Nitrous Oxide and paddy fields is not entirely incorrect.
Sulfur Dioxide (SO₂) is emitted through the combustion of coal and other sulfur-containing fuels. Brick Kilns using such fuels can emit SO₂, Particulate Matter, CO, and CO₂. SO₂ contributes to the formation of Acid Rain and Sulfate Aerosols. An important scientific distinction is that SO₂ is not classified as a major Greenhouse Gas. Consequently, the question's heading, ‘Greenhouse Gas—Source’, is not entirely scientifically consistent. Furthermore, the historical use of CFC-12 in automobile air conditioners is well established.