Microtheme: PollutionXImpact & remediation —
15 questions asked in Prelims in the past.

1. [2025] Statement I:
   Activated carbon is a good and an attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries. O
   Statement II :
   Activated carbon exhibits a large surface area and a strong potential for adsorbing heavy metals.
   Statement III :
   Activated carbon can be easily synthesized from environmental wastes with high carbon content.
   Which one of the following is correct in respect of the above statements?
   • (a) Both Statement II and Statement III are correct and both of them explain Statement I
   • (b) Both Statement II and Statement III are correct but only one of them explains Statement I
   • (c) Only one of the Statements II and III is correct and that explains Statement I
   • (d) Neither Statement II nor Statement III is correct
   Correct Answer: (A) Both Statement II and Statement III are correct and both of them explain Statement I
2. [2025] With reference to Direct Air Capture, an emerging technology, which of the following statements is/are correct?
   I. It can be used as a way of carbon sequestration.
   II. It can be a valuable approach for plastic production and in food processing.
   III. In aviation, it can be a source of carbon for combining with hydrogen to create synthetic low-carbon fuel.
   Select the correct answer using the code given below.
   • (a) I and II only
   • (b) II only
   • (c) I, II, and III
   • (d) None of the above statements is correct
   Correct Answer: (C) I, II, and III
3. [2023] With reference to the role of biofilters in Recirculating Aquaculture System, consider the following statements:
   1. Biofilters provide waste treatment by removing uneaten fish feed.
   2. Biofilters convert ammonia present in fish waste to nitrate.
   3. Biofilters increase phosphorus as nutrient for fish in water.
   How many of the statements given above are correct?
   • (a) Only one
   • (b) Only two
   • (c) All three
   • (d) None
   Correct Answer: (B) Only two
4. [2022] In the context of WHO Air Quality Guidelines, consider the following statements :
   1. The 24-hour mean of PM 2.5 should not exceed 15 μg/m3 and annual mean of PM 2.5 should not exceed 5 μg/m3.
   2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather.
   3. PM 10 can penetrate the long barrier and enter the bloodstream.
   4. Excessive ozone in the air can trigger asthma.
   Which of the statements given above are correct?
   • (a) 1,3 and 4
   • (b) 1 and 4 only
   • (c) 2,3 and 4
   • (d) 1 and 2 only
   Correct Answer: (B) 1 and 4 only
5. [2022] “Biorock Technology” is talked about in which one of the following situations?
   • (a) Restoration of damaged coral reefs
   • (b) Development of building materials using plant residues
   • (c) Identification of areas for exploration/extraction of shale gas
   • (d) Providing salt licks for wild animals in forests.
   Correct Answer: (A) Restoration of damaged coral reefs
6. [2021] R2 Code of Practices’ constitutes a tool available for promoting the adoption of
   • (a) environmentally responsible practices in electronics recycling industry
   • (b) ecological management of Wetlands of International Importance under the Ramsar Convention
   • (c) sustainable practices in the cultivation of agricultural crops in degraded land
   • (d) ‘Environmental Impact Assessment’ in the exploitation of natural resources
   Correct Answer: (A) environmentally responsible practices in electronics recycling industry
7. [2020] Steel slag can be the material for which of the following?
   1. Construction of base road
   2. Improvement of agricultural soil
   3. Production of cement
   Select the correct answer using the code given below:
   • (a) 1 and 2 only
   • (b) 2 and 3 only
   • (c) 1 and 3 only
   • (d) 1, 2 and 3
   Correct Answer: (D) 1, 2 and 3
8. [2020] In rural road construction, the use of which of the following is preferred for ensuring
   environmental sustainability or to reduce carbon footprint?
   1. Copper slag
   2. Cold mix asphalt technology
   3. Geotextiles
   4. Hot mix asphalt technology
   5. Portland cement
   Select the correct answer using the code given below:
   • (a) 1, 2 and 3 only
   • (b) 2, 3 and 4 only
   • (c) 4 and 5 only
   • (d) 1 and 5 only
   Correct Answer: (A) 1, 2 and 3 only
9. [2019] In the context of which one of the following are the terms ‘pyrolysis and plasma gasification’ mentioned?
   • (a) Extraction of rare earth elements
   • (b) Natural gas extraction technologies
   • (c) Hydrogen fuel-based automobiles
   • (d) Waste-to-energy technologies
   Correct Answer: (D) Waste-to-energy technologies
10. [2018] Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds ?
    1.Decreased salinity in the river
    2.Pollution of groundwater
    3.Lowering of the water-table
    Select the correct answer using the code given below :
    • (a) 1 only
    • (b) 2 and 3 only
    • (c) 1 and 3 only
    • (d) 1, 2 and 3
    Correct Answer: (B) 2 and 3 only
11. [2017] In the context of solving pollution problems what is/are the
    advantage/disadvantages of bioremediation technique?
    1. It is a technique for cleaning up pollution by enhancing the same biodegradation process
    that occurs in nature.
    2. Any contaminant with heavy metals such as cadmium and lead can be readily and
    completely treated by bioremediation using microorganisms.
    3. Genetic engineering can be used to create microorganisms specifically designed for
    bioremediation.
    Select the correct answer using the code given below:
    • (a) 1 only
    • (b) 2 and 3 only
    • (c) 1 and 3 only
    • (d) 1, 2 and 3
    Correct Answer: (C) 1 and 3 only
12. [2015] With reference to ‘fly ash’ produced by the power plants using coal as fuel, which of the
    following statements is/are correct?
    (1) Fly ash can be used in the production of bricks for building construction.
    (2) Fly ash can be used as a replacement for some of the Portland cement contents of concrete.
    (3) Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic
    elements.
    Select the correct answer using the code given below.
    • (a) 1 and 2
    • (b) 2 only
    • (c) 1 and 3
    • (d) 3 only
    Correct Answer: (A) 1 and 2
13. [2011] In the Union Budget 2011-12, a full exemption from the basic customs duty was extended to the bio-based asphalt (bioasphalt). What is the importance of this material?
    1. Unlike traditional asphalt, bio-asphalt is not based on fossil fuels.
    2. Bioasphalt can be made from non-renewable resources.
    3. Bioasphalt can be made from organic waste materials.
    4. It is eco-friendly to use bioasphalt for surfacing of the roads.
    Which of the statements given above are correct?
    • (a) 1, 2 and 3 only
    • (b) 1, 3 and 4 only
    • (c) 2 and 4 only
    • (d) 1, 2, 3 and 4
    Correct Answer: (B) 1, 3 and 4 only
14. [2010] Excessive release of the pollutant carbon monoxide (CO) into the air may produce a condition in which oxygen supply in the human body decreases. What causes this condition?
    • (a) When inhaled into the human body CO is converted into CO2
    • (b) The inhaled CO has much higher affinity for haemoglobin as compared to oxygen
    • (c) The inhaled CO destroys the chemical structure of haemoglobin
    • (d) The inhaled CO adversely affects the respiratory centre in the brain
    Correct Answer: (B) The inhaled CO has much higher affinity for haemoglobin as compared to oxygen
15. [2010] Which bacterial strain, developed from natural isolated by genetic manipulations, can be used for treating oil spills?
    • (a) Agrodbacterium
    • (b) Clostridium
    • (c) Nitrosomonas
    • (d) Pseudomonas
    Correct Answer: (D) Pseudomonas