Minimalist IAS
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 →

निम्नलिखित कथनों पर विचार कीजिए :

  1. कथन I: चक्रीय अर्थव्यवस्था ग्रीनहाउस गैसों के उत्सर्जन को कम करती है।
  2. कथन II: चक्रीय अर्थव्यवस्था आगत के रूप में कच्चे माल के प्रयोग को कम करती है।
  3. कथन III: चक्रीय अर्थव्यवस्था उत्पादन प्रक्रिया में अपव्यय को कम करती है।

उपर्युक्त कथनों के संदर्भ में, निम्नलिखित में से कौन-सा एक सही है?

Read this question in English

Consider the following statements:

Statement-I. Circular economy reduces the emissions of greenhouse gases.

Statement-II. Circular economy reduces the use of raw materials as inputs.

Statement-III. Circular economy reduces wastage in the production process.

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

उत्तर और व्याख्या · explanation in English

Answer: (a) कथन II और कथन III दोनों सही हैं तथा वे दोनों कथन I की व्याख्या करते हैं

A circular economy keeps materials in use through reuse, repair and recycling instead of the 'take–make–dispose' model. Using fewer fresh raw materials cuts the energy spent extracting and processing them, and cutting waste cuts the emissions from producing and disposing of it, so both II and III explain the fall in greenhouse gas emissions.

  • ✓ Statement-I The European Parliament lists a reduction in total annual greenhouse gas emissions among the benefits of a circular economy.
  • ✓ Statement-II Reusing and recycling products slows the use of natural resources, so fewer virgin raw materials are needed; this lowers emissions from mining and processing.
  • ✓ Statement-III Better design and efficient production reduce waste and the energy and resources consumed, which also lowers emissions.

Remember · Circular economy = reduce, reuse, repair, recycle. Fewer raw materials and less waste mean less energy use and lower greenhouse gas emissions.

Sources

  • European Parliament, Circular economy: definition, importance and benefits (2023) ↗ “Parliament wants Europeans to switch to a circular economy by using raw materials more efficiently and reducing waste. … Another benefit from the circular economy is a reduction in total annual greenhouse gas emissions. Creating more efficient and sustainable products from the start would help to reduce energy and resource consumption”

Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

निम्नलिखित पर विचार कीजिए :

  1. I.धूम्रपान के बाद सिगरेट के बचे हुए टुकड़े
  2. II.चश्मे के लेंस
  3. III.कार के टायर

उपर्युक्त में से कितनों में प्लास्टिक होता है?

Read this question in English

Consider the following:

I. Cigarette butts

II. Eyeglass lenses

III. Car tyres

How many of them contain plastic?

(a) Only one · (b) Only two · (c) All the three · (d) None

उत्तर और व्याख्या · explanation in English

Answer: (c) सभी तीन

All three contain plastic. Cigarette filters are made mainly of cellulose acetate fibres, which are microplastics; many eyeglass lenses are plastic (for example CR-39 and polycarbonate); and tiny plastic particles are shed by car tyres as they wear.

  • ✓ I The WHO Framework Convention on Tobacco Control Secretariat says cigarette filters are mainly composed of microplastics known as cellulose acetate fibres.
  • ✓ II Many spectacle lenses are made of plastic: a peer-reviewed study of spectacle lens materials covers CR-39, polycarbonate and Trivex, and calls CR-39 lenses the most basic form of plastic lenses.
  • ✓ III IUCN counts particles worn off car tyres among the tiny plastic particles that reach the oceans.

Remember · Cigarette filters (cellulose acetate), eyeglass lenses (CR-39, polycarbonate) and car tyres (which shed microplastics) all contain plastic.

Sources

Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). Permalink ·

निम्नलिखित कथनों पर विचार कीजिए :

  1. कथन I: सक्रियित कार्बन बहिःस्रावी धाराओं में से प्रदूषकों को हटाने और विभिन्न उद्योगों से आने वाले संदूषकों के उपचारण हेतु एक अच्छा और आकर्षक साधन है।
  2. कथन II: सक्रियित कार्बन का एक वृहत् पृष्ठ क्षेत्रफल होता है और उसमें भारी धातुओं को अधिशोषित करने की दमदार शक्यता है।
  3. कथन III: सक्रियित कार्बन, उच्च कार्बन अंश वाले वातावरणीय अपशिष्टों में से आसानी से संश्लेषित किया जा सकता है।

उपर्युक्त कथनों के बारे में, निम्नलिखित में से कौन-सा एक सही है?

Read this question in English

Consider the following statements:

Statement I. Activated carbon is a good and an 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?

(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

उत्तर और व्याख्या · explanation in English

Answer: (a) कथन II और कथन III दोनों सही हैं तथा वे दोनों कथन I की व्याख्या करते हैं

Both Statement II and Statement III are correct, and both explain Statement I. A large surface area lets activated carbon hold heavy metals and other pollutants on its surface, and because it can be made cheaply from carbon-rich waste, it becomes an attractive tool for cleaning effluents.

  • ✓ II Activated carbon is highly porous, with a very large surface area and strong adsorption capacity. Pollutants stick to that surface (adsorption), which is exactly how it strips heavy metals from wastewater. This explains why it removes pollutants (Statement I).
  • ✓ III Farm and other carbon-rich wastes are the usual raw material for activated carbon, and the process is simple and cheap. This low cost explains why it is 'attractive' as a treatment tool (Statement I).
  • ✗ (b) This option says only one of II and III explains Statement I. But the ability to adsorb (II) explains the 'good' part and the cheap, waste-based supply (III) explains the 'attractive' part, so both explain it.
  • ✗ (d) Both statements are supported by published research on biomass-derived activated carbon, so 'neither is correct' fails.

Remember · Activated carbon = porous, huge surface area, strong adsorbent, cheaply made from carbon-rich waste; hence widely used to clean effluents.

Sources

  • Adsorption of heavy metal onto biomass-derived activated carbon: review (RSC Advances, via NIH/PMC) ↗ “Biomass-derived activated carbon adsorbents offer large adjustable specific surface area, hierarchically porous structure, strong adsorption capacity, and excellent high economic applicability. … Agricultural waste is usually the first choice to prepare biomass-derived activated carbon, attributing to its high specific surface area, high stability, excellent adsorption properties, simple production process and low price.”

Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

वायु प्रदूषण कम करने हेतु कृत्रिम वर्षा कराने के तरीके में किनका प्रयोग होता है?

Read this question in English

Artificial way of causing rainfall to reduce air pollution makes use of

(a) silver iodide and potassium iodide · (b) silver nitrate and potassium iodide · (c) silver iodide and potassium nitrate · (d) silver nitrate and potassium chloride

उत्तर और व्याख्या · explanation in English

Answer: (a) सिल्वर आयोडाइड और पोटैशियम आयोडाइड

Artificial rain is made by cloud seeding: seed particles are added to a cloud so that rain can form, and Delhi has trialled it as an emergency measure against pollution episodes. India's IITM names silver iodide as the standard seeding agent for cold clouds, and UPSC's key pairs it with potassium iodide.

  • ✓ (a) Both agents are iodides. IITM's CAIPEEX pages name silver iodide (AgI) as the ice-nucleating agent used in glaciogenic seeding; UPSC's key names potassium iodide as the second agent, which the IITM pages do not mention.
  • ✗ (b) Silver nitrate replaces silver iodide here; the key's answer has both agents as iodides.
  • ✗ (c) Potassium nitrate replaces potassium iodide here; the key's answer has both agents as iodides.
  • ✗ (d) Silver nitrate and potassium chloride replace both iodides.

Remember · Cloud seeding uses iodide salts, chiefly silver iodide (with potassium iodide in the key), to trigger rain.

Sources

Question and answer: UPSC's official GS Paper I (2025, 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.

See the whole X-Ray →

The same topic in Mains