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Q1Environment·Environmental PollutionPYQ 2025
Consider the following:
1. Cigarette butts
2. Eyeglass lenses
3. Car tyres
How many of them contain plastic?
- AOnly one
- BOnly two
- CAll the threeCorrect
- DNone
Explanation
Correct. Cigarette butts contain cellulose acetate (a plastic), eyeglass lenses are made of polycarbonate or CR-39 plastic, and car tyres contain synthetic rubber polymers which are classified as plastic.
Why the other options are incorrect
- Option A
All three items contain plastic polymers, not just one.
- Option B
All three contain plastic, not just two.
- Option D
All three items contain various forms of plastic polymers.
Q2Environment·Environmental PollutionPYQ 2025
Consider the following statements:
Statement I: Activated carbon is a good and attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries.
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?
- ABoth Statement II and Statement III are correct and both of them explain Statement ICorrect
- BBoth Statement II and Statement III are correct but only one of them explains Statement I
- COnly one of the Statements II and III is correct and that explains Statement I
- DNeither Statement II nor Statement III is correct
Explanation
Correct. Activated carbon's large surface area (Statement II) enables it to adsorb pollutants effectively, and its easy synthesis from waste biomass (Statement III) makes it an attractive remediation tool. Both explain Statement I.
Why the other options are incorrect
- Option B
Both statements are correct and both contribute to explaining why activated carbon is an attractive remediation tool.
- Option C
Both Statement II and Statement III are factually correct, not just one.
- Option D
Both statements are correct. Activated carbon does have a large surface area for adsorption and can be made from agricultural waste and other carbon-rich materials.
Q3Environment·Environmental PollutionPYQ 2025
Artificial way of causing rainfall to reduce air pollution makes use of which of the following?
- ASilver iodide and potassium iodideCorrect
- BSilver nitrate and potassium iodide
- CSilver iodide and potassium nitrate
- DSilver nitrate and potassium chloride
Explanation
Correct. Cloud seeding uses silver iodide and potassium iodide as nucleating agents to induce artificial rainfall, which helps wash out particulate pollutants from the atmosphere.
Why the other options are incorrect
- Option B
Silver nitrate is not the standard cloud-seeding agent; silver iodide is preferred because its crystal structure closely resembles that of ice.
- Option C
While silver iodide is correct, potassium nitrate is not the standard companion salt used in cloud seeding for pollution control.
- Option D
Neither silver nitrate nor potassium chloride is the standard agent for cloud seeding to reduce air pollution.
Q4Environment·Environmental PollutionPYQ 2024
With reference to Perfluoroalkyl and polyfluoroalkyl substances (PFAS) that are used in making many consumer products, consider the following statements:
1. PFAS are man-made chemicals that are not found naturally in the environment.
2. PFAS are called 'forever chemicals' because they do not degrade in the environment.
3. PFAS can accumulate in the human body over time.
Which of the statements given above are correct?
- A1 and 2 only
- B2 and 3 only
- C1 and 3 only
- D1, 2 and 3Correct
Explanation
Correct. PFAS are synthetic (Statement 1), are called 'forever chemicals' because they persist without degrading (Statement 2), and bioaccumulate in the human body (Statement 3).
Why the other options are incorrect
- Option A
Statement 3 is also correct. PFAS bioaccumulate in human blood and organs due to their extreme chemical stability.
- Option B
Statement 1 is also correct. PFAS are entirely synthetic; they do not occur naturally in the environment.
- Option C
Statement 2 is also correct. The carbon-fluorine bond in PFAS is extremely strong, making them resistant to environmental degradation.
Q5Environment·Environmental PollutionPYQ 2024
According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions?
- AVehicular exhaust
- BVolcanic eruptions
- CPetroleum refining
- DBurning of fossil fuels in power plantsCorrect
Explanation
Correct. The EPA identifies fossil fuel combustion at power plants, especially coal-fired plants, as the largest source of SO2 emissions due to the sulphur content in coal.
Why the other options are incorrect
- Option A
Vehicles primarily emit nitrogen oxides and particulate matter. SO2 from vehicles is relatively minor compared to power plant emissions.
- Option B
Volcanic eruptions are a natural source of SO2 but are not the largest anthropogenic source tracked by EPA.
- Option C
Petroleum refining emits some SO2 but the quantity is far less than from coal-fired power generation.
Q6Environment·Environmental PollutionPYQ 2024
'Membrane Bioreactors' are often discussed in the context of:
- ADesalination of seawater
- BGenetic engineering of microbes
- CProduction of biofuels from algae
- DWastewater treatmentCorrect
Explanation
Correct. Membrane bioreactors combine biological degradation of organic matter with membrane filtration to treat wastewater, producing high-quality effluent suitable for reuse.
Why the other options are incorrect
- Option A
Membrane bioreactors combine biological treatment with membrane filtration and are not typically used for desalination, which relies on reverse osmosis.
- Option B
Membrane bioreactors are wastewater treatment systems, not tools for genetic modification of microorganisms.
- Option C
While membranes can be used in some biofuel processes, membrane bioreactors are specifically designed for and discussed in the context of sewage and wastewater treatment.
Q7Environment·Environmental PollutionPYQ 2023
With reference to the role of biofilters in Recirculating Aquaculture System, consider the following statements:
1. Biofilters provide a medium for nitrifying bacteria that convert ammonia to nitrate.
2. Biofilters increase the dissolved oxygen content in water.
Which of the statements given above is/are correct?
- A1 only
- BBoth 1 and 2Correct
- C2 only
- DNeither 1 nor 2
Explanation
Correct. Biofilters host nitrifying bacteria (Nitrosomonas and Nitrobacter) that convert toxic ammonia to less toxic nitrate (Statement 1), and the trickling of water through the filter media also helps increase dissolved oxygen (Statement 2).
Why the other options are incorrect
- Option A
Statement 2 is also correct in the context of certain biofilter designs that aerate the water as it passes through the filter media.
- Option C
Statement 1 is the primary function of biofilters in aquaculture — converting ammonia via nitrification.
- Option D
Both statements are correct. Ammonia conversion is the core function, and oxygenation is an additional benefit of the biofilter design.
Q8Environment·Environmental PollutionPYQ 2023
Consider the following statements regarding mercury pollution:
1. TheMinamata Convention)__ on Mercury is a global treaty to protect human health and the environment from the adverse effects of mercury.
2. Mercury is released into the environment primarily through volcanic eruptions and weathering of rocks only.
3. Artisanal and small-scale gold mining is the largest source of anthropogenic mercury emissions globally.
Which of the statements given above is/are correct?
- A1 only
- B1 and 2 only
- C1 and 3 onlyCorrect
- D1, 2 and 3
Explanation
Correct. The Minamata Convention is indeed a global mercury treaty (Statement 1), and artisanal gold mining is the largest anthropogenic mercury source (Statement 3). Statement 2 is wrong because it excludes major anthropogenic sources.
Why the other options are incorrect
- Option A
Statement 3 is also correct. UNEP identifies artisanal gold mining as the single largest anthropogenic mercury source.
- Option B
Statement 2 is incorrect because mercury is also released by coal combustion, waste incineration, and industrial processes, not only by natural sources.
- Option D
Statement 2 is incorrect. While volcanic eruptions and rock weathering are natural sources, mercury is also released by coal burning, cement production, and industrial activities.
Q9Environment·Environmental PollutionPYQ 2022
Consider the following:
1. Aerosols
2. Foam agents
3. Fire retardants
4. Lubricants
In thecontext of ozonedepletion, which of the above can beCFC-containingproducts?
- A1 and 4 only
- B1, 2 and 3 only
- C2, 3 and 4 only
- D1, 2, 3 and 4Correct
Explanation
Correct. CFCs have been used as aerosol propellants, foam-blowing agents, fire retardants (Halons are related), and as lubricant solvents in industrial applications.
Why the other options are incorrect
- Option A
Foam agents and fire retardants can also contain CFCs, so excluding them is incorrect.
- Option B
Lubricants, particularly certain industrial-grade ones, have also used CFCs as solvents, so all four are correct.
- Option C
Aerosol propellants were among the earliest and largest uses of CFCs, so excluding them is incorrect.
Q10Environment·Environmental PollutionPYQ 2022
In the context of WHO Air Quality Guidelines, consider the following statements:
1. Theupdated WHO guidelinestighten the recommended limits for all the classical pollutants.
2. Particulate Matter (PM2.5) WHO guideline annual mean has beenreviseddownward from 10 µg/m³ to 5 µg/m³.
3. WHO Air Quality Guidelines arelegally binding on all member nations.
Which of the statements given above is/are correct?
- A1 and 3 only
- B1 and 2 onlyCorrect
- C2 and 3 only
- D1, 2 and 3
Explanation
Correct. The 2021 WHO guidelines tightened limits for all classical pollutants (Statement 1) and reduced the PM2.5 annual mean from 10 to 5 µg/m³ (Statement 2). They are not legally binding (Statement 3 is wrong).
Why the other options are incorrect
- Option A
Statement 3 is incorrect. WHO guidelines are advisory, not legally binding.
- Option C
Statement 1 is also correct. The 2021 update tightened all recommended limits. Statement 3 is wrong as WHO guidelines are advisory.
- Option D
Statement 3 is incorrect. WHO Air Quality Guidelines are recommendations, not legally binding instruments. Each country sets its own national ambient air quality standards.
Q11Environment·Environmental PollutionPYQ 2021
'R2 Code of Practices' constitutes a tool available for promoting the adoption of:
- AEnvironmentallysound management of e-wasteCorrect
- BSustainabletextiles manufacturing
- CFood safetyinprocessed food industry
- DResponsible mining of rare earth elements
Explanation
Correct. R2 (Responsible Recycling) is a certification standard for electronics recyclers, promoting environmentally sound management of e-waste through responsible recycling practices.
Why the other options are incorrect
- Option B
R2 is specific to electronics recycling, not to textile manufacturing.
- Option C
R2 has no connection to food safety. It is an e-waste management standard.
- Option D
R2 deals with electronics recycling, not mining of rare earth elements.
Q12Environment·Environmental PollutionPYQ 2021
Why is there a concern about copper smelting plants?
1. They may releasesulphur dioxide as a pollutant.
2.They may releasearsenic as a pollutant.
Select the correct answer using the code given below:
- A1 only
- BBoth 1 and 2Correct
- C2 only
- DNeither 1 nor 2
Explanation
Correct. Copper smelting releases SO2 from the sulphide ores being processed (Statement 1) and arsenic because it is a common impurity in copper ores (Statement 2).
Why the other options are incorrect
- Option A
Arsenic is also released from copper smelting because copper ores frequently contain arsenic as an impurity.
- Option C
SO2 is a major emission from copper smelting since copper is predominantly extracted from sulphide ores.
- Option D
Both pollutants are genuine concerns. The Sterlite copper smelter controversy in Thoothukudi highlighted these pollution issues.