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Environment & ecology

Prelims · Environment & ecology · 40 questions

Pollution & waste

Every UPSC Prelims question on this topic, 2016–2026, newest first. Tap an option to check yourself; the answer and explanation open below it.

Pollution & waste questions per year: 2016: 1, 2017: 2, 2018: 1, 2019: 5, 2020: 2, 2021: 6, 2022: 3, 2023: 2, 2024: 4, 2025: 4, 2026: 0 Asked in 10 of 11 years · most in 2021 (6)

Practising Environment & ecology? Take it as timed sets of 25 →

UPSC syllabus: “General issues on Environmental ecology, Bio-diversity and Climate Change - that do not require subject specialization.” Sub-topics in the detailed syllabus →

Showing 31–40 of 40, newest first.

Prelims 2019 · Q41

Medium

निम्नलिखित कथनों पर विचार कीजिए :

  1. 1.कृषि मृदाएँ पर्यावरण में नाइट्रोजन के ऑक्साइड निर्मुक्त करती हैं।
  2. 2.मवेशी पर्यावरण में अमोनिया निर्मुक्त करते हैं।
  3. 3.कुक्कुट उद्योग पर्यावरण में अभिक्रियाशील नाइट्रोजन यौगिक निर्मुक्त करते हैं।

उपर्युक्त में से कौन-सा/से कथन सही है/हैं?

Read this question in English

Consider the following statements:

1. Agricultural soils release nitrogen oxides into environment.

2. Cattle release ammonia into environment.

3. Poultry industry releases reactive nitrogen compounds into environment.

Which of the statements given above is/are correct?

(a) 1 and 3 only · (b) 2 and 3 only · (c) 2 only · (d) 1, 2 and 3

उत्तर और व्याख्या · explanation in English

Answer: (d) 1, 2 और 3

All three statements are correct, because farming is a major source of reactive nitrogen. Fertilised soils release nitrous oxide, and manure and urine from cattle and poultry give off ammonia.

  • ✓ 1. When reactive nitrogen such as fertiliser reaches the soil, microbes convert part of it into nitrous oxide, an oxide of nitrogen and a greenhouse gas.
  • ✓ 2. Much of the protein that cattle eat is lost in manure and urine, and this nitrogen escapes as ammonia and other nitrogenous gases.
  • ✓ 3. Poultry waste is rich in nitrogen, and under aerobic conditions it can evaporate as ammonia, which is a reactive nitrogen compound.

Remember · Agriculture is a big source of reactive nitrogen: soils give nitrous oxide, while cattle and poultry manure gives ammonia.

Sources

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2019 · Q43

X-Ray · Core #50 Hard

सार्वजनिक परिवहन में बसों के लिए ईंधन के रूप में हाइड्रोजन संवर्धित CNG (H-CNG) का इस्तेमाल करने के प्रस्तावों के संदर्भ में, निम्नलिखित कथनों पर विचार कीजिए :

  1. 1.H-CNG के इस्तेमाल का मुख्य लाभ कार्बन मोनोक्साइड के उत्सर्जनों का विलोपन है।
  2. 2.ईंधन के रूप में H-CNG कार्बन डाइऑक्साइड और हाइड्रोकार्बन उत्सर्जनों को कम करती है।
  3. 3.बसों के लिए ईंधन के रूप में CNG के साथ हाइड्रोजन को आयतन के आधार पर पाँचवें हिस्से तक मिलाया जा सकता है।
  4. 4.CNG की अपेक्षा H-CNG ईंधन को कम खर्चीला बनाती है।

उपर्युक्त में से कौन-सा/से कथन सही है/हैं?

Read this question in English

In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements:

1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.

2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.

3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.

4. H-CNG makes the fuel less expensive than CNG.

Which of the statements given above is/are correct?

(a) 1 only · (b) 2 and 3 only · (c) 4 only · (d) 1, 2, 3 and 4

उत्तर और व्याख्या · explanation in English

Answer: (b) केवल 2 और 3

Statements 2 and 3 are correct. Blending hydrogen, which has no carbon, into CNG lowers carbon dioxide and hydrocarbon emissions, and India's trials and rules use a blend of about 18% hydrogen by volume, which is within one-fifth. H-CNG does not eliminate carbon monoxide and is not cheaper than plain CNG.

  • ✗ 1. H-CNG is still mostly natural gas, a carbon fuel, so it can lower carbon monoxide but cannot eliminate it. Official pages describe the benefit as emissions reduction, not elimination.
  • ✓ 2. Part of the fuel is carbon-free hydrogen, so less carbon is burnt per unit of energy and the blend gives lower carbon dioxide and hydrocarbon emissions; the Petroleum Ministry calls H-CNG an interim technology for emissions reduction.
  • ✓ 3. The Road Transport Ministry allowed H-CNG with an 18% hydrogen mix in CNG engines, which is under one-fifth (20%) by volume; the Delhi bus trials also used 18%.
  • ✗ 4. Making the blend is costly: the Petroleum Ministry notes that the high cost of producing and blending hydrogen offsets the fuel-economy savings over plain CNG, and its Secretary called commercial viability the main challenge.
  • • Since then After the exam year, the Road Transport Ministry notified (GSR 585(E), 25 September 2020) H-CNG with an 18% hydrogen mix as an automotive fuel.

Remember · H-CNG is CNG blended with up to about 18% hydrogen by volume: it lowers emissions but does not remove them, and it is costlier than plain CNG.

Sources

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2019 · Q59

X-Ray · Core #60 Medium

भारत में ठोस अपशिष्ट प्रबंधन नियम, 2016 के अनुसार, निम्नलिखित में से कौन-सा एक कथन सही है?

Read this question in English

As per the Solid Waste Management Rules, 2016 in India, which one of the following statements is correct?

(a) Waste generator has to segregate waste into five categories. · (b) The Rules are applicable to notified urban local bodies, notified towns and all industrial townships only. · (c) The Rules provide for exact and elaborate criteria for the identification of sites for landfills and waste processing facilities. · (d) It is mandatory on the part of waste generator that the waste generated in one district cannot be moved to another district.

उत्तर और व्याख्या · explanation in English

Answer: (c) इन नियमों में अपशिष्ट भराव स्थलों तथा अपशिष्ट प्रसंस्करण सुविधाओं के लिए सटीक और ब्यौरेवार मानदंड उपबंधित हैं।

Option (c) is correct because Schedule I of the Solid Waste Management Rules, 2016 gives detailed site-selection criteria for sanitary landfills, such as minimum distances from rivers, ponds, highways, habitations and airports. The other three options misstate the rules.

  • ✗ (a) Rule 4 asks every waste generator to segregate waste into three streams: bio-degradable, non bio-degradable and domestic hazardous waste. There is no five-way split.
  • ✗ (b) Rule 2 applies the Rules far more widely than 'only' urban local bodies, notified towns and industrial townships. It also covers census towns, outgrowths of urban agglomerations, railways, airports, ports, defence establishments, SEZs and more.
  • ✓ (c) Schedule I lays down criteria such as a landfill 100 metres from a river, 200 metres from a pond, highways, habitations, public parks and water supply wells, and 20 km from airports.
  • ✗ (d) The Rules contain no ban on moving waste between districts. They say the State Pollution Control Board regulates inter-State movement of waste.
  • • Since then The Solid Waste Management Rules, 2016 have since been superseded by the Solid Waste Management Rules, 2026, notified in January 2026 and in force from 1 April 2026. The new Rules make four-stream segregation (wet, dry, sanitary and special care waste) mandatory (PIB).

Remember · Under the 2016 Rules, waste is segregated into three streams and Schedule I fixes landfill siting distances; the 2026 Rules replaced these with four-stream segregation.

Sources

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2019 · Q78

X-Ray · Core #10 Medium

भारत में निम्नलिखित में से किसमें एक महत्त्वपूर्ण विशेषता के रूप में ‘विस्तारित उत्पादक दायित्व’ आरंभ किया गया था?

Read this question in English

In India, 'extended producer responsibility' was introduced as an important feature in which of the following?

(a) The Bio-medical Waste (Management and Handling) Rules, 1998 · (b) The Recycled Plastic (Manufacturing and Usage) Rules, 1999 · (c) The e-Waste (Management and Handling) Rules, 2011 · (d) The Food Safety and Standard Regulations, 2011

उत्तर और व्याख्या · explanation in English

Answer: (c) ई-अपशिष्ट (प्रबंधन और हस्तन) नियम, 2011

India's e-Waste (Management and Handling) Rules, 2011 introduced extended producer responsibility (EPR), which makes the producer of electrical and electronic equipment answerable for the product until its safe disposal after use. The rules were notified in May 2011 and came into force on 1 May 2012.

  • ✓ (c) The official guidelines on these rules say they place the main responsibility for e-waste on producers of electrical and electronic equipment by introducing the concept of extended producer responsibility.
  • ✗ (a) The 1998 bio-medical waste rules pre-date the e-waste rules and are not the ones credited with bringing in EPR.
  • ✗ (b) The 1999 recycled plastics rules likewise pre-date the 2011 e-waste rules, which are the ones that introduced EPR in India.
  • ✗ (d) The Food Safety and Standards Regulations, 2011 deal with food safety, not with waste, so producer responsibility for end-of-life products is not their feature.

Remember · EPR = the producer stays responsible for a product until its safe disposal. In India it came with the e-Waste Rules, 2011 (in force 1 May 2012).

Sources

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2018 · Q13

X-Ray · Core #54 Easy

निम्नलिखित में से कौन-सा/से मानव क्रियाकलापों के कारण हाल में बहुत अधिक संकुचित हो गया है / सूख गया है ?

  1. 1.अराल सागर
  2. 2.काला सागर
  3. 3.बैकाल झील

नीचे दिए गए कूट का प्रयोग कर सही उत्तर चुनिए :

Read this question in English

Which of the following has/have shrunk immensely/dried up in the recent past due to human activities?

1. Aral Sea

2. Black Sea

3. Lake Baikal

Select the correct answer using the code given below:

(a) 1 only · (b) 2 and 3 · (c) 2 only · (d) 1 and 3

उत्तर और व्याख्या · explanation in English

Answer: (a) केवल 1

Only the Aral Sea fits. From the 1960s the Soviet Union diverted its feeder rivers, the Amu Darya and Syr Darya, to irrigate cotton, and the lake that was once the world's fourth largest broke into small remnants. The Black Sea and Lake Baikal have not shrunk in this way.

  • ✓ 1. Irrigation diversions starved the Aral Sea (on the Kazakhstan–Uzbekistan border) of inflow; satellite images show it was already a fraction of its 1960 extent by 2000.
  • ✗ 2. The Black Sea, a large inland sea linked to the Mediterranean through the Bosporus, faces pollution problems but has not dried up.
  • ✗ 3. Lake Baikal in Siberia, the world's deepest lake, still holds its vast volume of fresh water; it has not shrunk immensely.

Remember · Aral Sea: once the world's fourth-largest lake, fed by the Amu Darya and Syr Darya; shrank drastically after Soviet-era irrigation diversions from the 1960s.

Sources

  • World of Change: Shrinking Aral Sea, NASA Earth Observatory ↗ “In the 1960s, the Soviet Union undertook a major water diversion project on the arid plains of Kazakhstan, Uzbekistan, and Turkmenistan. … The lake they made, the Aral Sea , was once the fourth largest in the world. Although irrigation made the desert bloom, it devastated the Aral Sea.”

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2018 · Q81

Medium

निम्नलिखित में से कौन-सा/से नदी तल में बहुत अधिक बालू खऩन का/के संभावित परिणाम हो सकता है/सकते हैं ?

  1. 1.नदी की लवणता में कमी
  2. 2.भौमजल का प्रदूषण
  3. 3.भौम जलस्तर का नीचे चले जाना

नीचे दिए गए कूट का प्रयोग कर सही उत्तर चुनिए :

Read this question in English

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

उत्तर और व्याख्या · explanation in English

Answer: (b) केवल 2 और 3

Heavy sand mining harms groundwater in two ways: it can pollute it and it can pull the water-table down. It does not lower river salinity; near the coast it makes salt-water intrusion more likely.

  • ✗ 1. Removing sand deepens the channel and weakens natural barriers, so salt water can enter aquifers; UNEP lists 'salination of aquifers' as a result of sand extraction. Salinity goes up, not down.
  • ✓ 2. The sand layer filters water that seeps into the ground. The MoEFCC guidelines say mining can pollute groundwater by thinning this filter material, especially over recharge fissures.
  • ✓ 3. Mining lowers the riverbed and river level, and groundwater in the adjoining flood plain drains towards it, so the water-table falls. The guidelines record this as a listed effect.

Remember · Heavy riverbed sand mining lowers the water-table, weakens the sand filter that protects groundwater, and raises salt intrusion risk near the coast.

Sources

Question and answer: UPSC's official GS Paper I (2018, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2017 · Q14

Medium

प्रदूषण की समस्याओं का समाधान करने के सन्दर्भ में, जैवोपचारण (बायोरेमीडिएशन) तकनीक के कौन-सा/से लाभ है/हैं ?

  1. 1.यह प्रकृति में घटित होने वाली जैवनिम्नीकरण प्रक्रिया का ही संवर्धन कर प्रदूषण को स्वच्छ करने की तकनीक है ।
  2. 2.कैडमियम और लेड जैसी भारी धातुओं से युक्त किसी भी संदूषक को सूक्ष्मजीवों के प्रयोग से जैवोपचारण द्वारा सहज ही और पूरी तरह उपचारित किया जा सकता है ।
  3. 3.जैवोपचारण के लिए विशेषतः अभिकल्पित सूक्ष्मजीवों को सृजित करने के लिए आनुवंशिक इंजीनियरी (जेनेटिक इंजीनियरिंग) का उपयोग किया जा सकता है ।

नीचे दिए गए कूट का प्रयोग कर सही उत्तर चुनिए :

Read this question in English

In the context of solving pollution problems, what is/are the advantage/advantages 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

उत्तर और व्याख्या · explanation in English

Answer: (c) केवल 1 और 3

Bioremediation speeds up the natural breakdown of pollutants by microbes, and microbes can be genetically engineered for the job. But microbes break down organic compounds; metals such as cadmium and lead are elements that cannot be degraded, only changed in form or immobilised, so statement 2 overclaims.

  • ✓ 1. It uses microorganisms that feed on or co-metabolise contaminants, boosting the same biodegradation that happens in nature by supplying nutrients, oxygen or other electron acceptors.
  • ✗ 2. Bioremediation is described as degrading organic contaminants. Heavy metals cannot be broken down by microbes, so 'readily and completely treated' is wrong; at best microbes change their chemical form.
  • ✓ 3. Biotechnology uses genetically modified microbes for bioremediation; in 1971 Ananda Mohan Chakrabarty developed a bacterium that could break down oil spills.

Remember · Bioremediation = microbes degrading organic pollutants (oil, solvents, pesticides); engineered microbes help. Heavy metals cannot be degraded, only transformed or immobilised.

📘 Read it in NCERT: Class 12 Biology, Ch 10 (practise this chapter) · Class 8 Curiosity, Ch 2 (practise this chapter)

Sources

  • US EPA, CLU-IN: Bioremediation Overview ↗ · reference work “Bioremediation uses microorganisms to degrade organic contaminants in soil, groundwater, sludge, and solids. The microorganisms break down contaminants by using them as an energy source or cometabolizing them with an energy source.”
  • NCERT Class 12 · Biology, Chapter 10 “using genetically modified microbes, fungi, plants and animals. The applications of biotechnology include therapeutics, diagnostics, genetically modified crops for agriculture, processed food, bioremediation, waste treatment, and energy production.”
  • NCERT Class 8 · Curiosity, Chapter 2 “In 1971, he developed a special bacterium that could break down oil spills, helping to clean the environment.”

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2017 · Q59

Easy

जैव ऑक्सीजन माँग (BOD) किसके लिए एक मानक मापदंड है ?

Read this question in English

Biological Oxygen Demand (BOD) is a standard criterion for

(a) Measuring oxygen levels in blood · (b) Computing oxygen levels in forest ecosystems · (c) Pollution assay in aquatic ecosystems · (d) Assessing oxygen levels in high altitude regions

उत्तर और व्याख्या · explanation in English

Answer: (c) जलीय पारिस्थितिक तंत्रों में प्रदूषण के आमापन के लिए

BOD is the amount of oxygen that bacteria would use up to break down the organic matter in a sample of water, so it is a standard test of how polluted water is. A higher BOD means more organic pollution.

  • ✓ (c) BOD measures the oxygen consumed by microbes in decomposing the organic matter in water, so it works as an indirect measure of that matter. The greater the BOD of waste water, the greater its polluting potential.
  • ✗ (a) BOD is a test on water samples. It has nothing to do with the oxygen carried in blood.
  • ✗ (b) BOD says nothing about oxygen in forests. It tells us how much oxygen microbes need in water that carries organic waste.

Remember · BOD is oxygen bacteria need to decompose the organic matter in water. Higher BOD means more pollution; sewage treatment aims to bring it down.

📘 Read it in NCERT: Class 12 Biology, Ch 8 (practise this chapter) · Class 12 Biology, Ch 8 (practise this chapter)

Sources

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2017 · Q65

Medium

निम्नलिखित कथनों पर विचार कीजिए :

  1. 1.अल्पजीवी जलवायु प्रदूषकों को न्यूनीकृत करने हेतु जलवायु एवं स्वच्छ वायु गठबंधन (CCAC), G20 समूह के देशों की एक अनोखी पहल है ।
  2. 2.CCAC मेथैन, काला कार्बन एवं हाइड्रोफ्लुओरोकार्बनों पर केंद्रित करता है ।

उपर्युक्त कथनों में से कौन-सा/से सही है/हैं ?

Read this question in English

Consider the following statements:

1. Climate and Clean Air Coalition (CCAC) to Reduce Short Lived Climate Pollutants is a unique initiative of G20 group of countries.

2. The CCAC focuses on methane, black carbon and hydrofluorocarbons.

Which of the statements given above is/are correct?

(a) 1 only · (b) 2 only · (c) Both 1 and 2 · (d) Neither 1 nor 2

उत्तर और व्याख्या · explanation in English

Answer: (b) केवल 2

The Climate and Clean Air Coalition (CCAC) is a voluntary partnership convened within the UN Environment Programme (UNEP), not an initiative of the G20, so statement 1 is wrong. It targets methane, black carbon and hydrofluorocarbons, so statement 2 is correct.

  • ✗ 1. The CCAC was founded in 2012 and is convened within UNEP. It is a voluntary partnership of governments, intergovernmental organisations and non-governmental organisations, not a project of the G20 group.
  • ✓ 2. The CCAC works to cut short-lived climate pollutants: methane, black carbon, hydrofluorocarbons and tropospheric ozone. These stay in the air only briefly but heat the planet strongly and harm air quality.

Remember · CCAC (2012) is a UNEP-convened voluntary coalition on short-lived climate pollutants: methane, black carbon, HFCs and tropospheric ozone. It is not a G20 body.

Sources

  • UNEP: Climate and Clean Air Coalition (CCAC) ↗ “Founded in 2012, and convened within UNEP, The Climate and Clean Air Coalition (CCAC) is a voluntary partnership of more than 190 governments, intergovernmental organizations, and non-governmental organizations. … The CCAC works to reduce powerful but short-lived climate pollutants (SLCPs) – methane, black carbon, hydrofluorocarbons (HFCs), and tropospheric ozone – that drive both climate change and air pollution.”

Question and answer: UPSC's official GS Paper I (2017, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2016 · Q86

X-Ray · Core #13 Easy

हमारे देश के शहरों में वायु गुणता सूचकांक (Air Quality Index) का परिकलन करने में साधारणतया निम्नलिखित वायुमंडलीय गैसों में से किनको विचार में लिया जाता है?

  1. 1.कार्बन डाइऑक्साइड
  2. 2.कार्बन मोनोक्साइड
  3. 3.नाइट्रोजन डाइऑक्साइड
  4. 4.सल्फर डाइऑक्साइड
  5. 5.मेथैन

नीचे दिए गए कूट का प्रयोग कर सही उत्तर चुनिए।

Read this question in English

In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index?

1. Carbon dioxide

2. Carbon monoxide

3. Nitrogen dioxide

4. Sulfur dioxide

5. Methane

Select the correct answer using the code given below.

(a) 1, 2 and 3 only · (b) 2, 3 and 4 only · (c) 1, 4 and 5 only · (d) 1, 2, 3, 4 and 5

उत्तर और व्याख्या · explanation in English

Answer: (b) केवल 2, 3 और 4

Carbon monoxide, nitrogen dioxide and sulfur dioxide are used in India's National Air Quality Index; carbon dioxide and methane are not. The index is built from eight pollutants for which short-term air quality standards exist: PM10, PM2.5, NO2, SO2, CO, ozone, ammonia and lead.

  • ✗ 1. Carbon dioxide is a greenhouse gas, not one of the eight pollutants in the National AQI.
  • ✓ 2. Carbon monoxide (CO) is one of the eight AQI pollutants.
  • ✓ 3. Nitrogen dioxide (NO2) is one of the eight AQI pollutants.
  • ✓ 4. Sulfur dioxide (SO2) is one of the eight AQI pollutants.
  • ✗ 5. Methane is a greenhouse gas and is not among the eight pollutants used for the AQI.

Remember · National AQI pollutants: PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb. No CO2 and no methane.

📘 Read it in NCERT: Class 8 Curiosity, Ch 8 (practise this chapter)

Sources

  • About National Air Quality Index (Central Pollution Control Board) ↗ “AQ sub-index and health breakpoints are evolved for eight pollutants (PM10, PM2.5, NO2, SO2, CO, O3, NH3, and Pb) for which short-term (upto 24-hours) National Ambient Air Quality Standards are prescribed.”
  • NCERT Class 8 · Curiosity, Chapter 8 “The major pollutants present in the air are particulate matter (dust, soot) and gases like carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide. The air quality index (AQI) is a tool used to describe the air quality.”

Question and answer: UPSC's official GS Paper I (2016, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

The Syllabus X-Ray of this topic

2 of its 7 sub-topics are Core

2 Core · 2 High · 2 Steady · 1 Rare

  • Core #13Air pollution & air-quality standards · 11 questions
  • Core #60Solid, plastic & e-waste · 6 questions
  • HighSoil, noise & heavy-metal pollution · 5 questions
  • HighWater pollution & treatment · 3 questions

The X-Ray ranks all 928 sub-topics of the UPSC syllabus by what UPSC has asked since 2016. The 60 Prelims Core sub-topics are behind 51% of Prelims questions.

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The same topic in Mains

Read it in NCERT

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