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Q35 (IAS/2019) Environment & Ecology › Pollution & Conservation › Agricultural pollution Official Key

Consider the following : 1. Carbon monoxide 2. Methane 3. Ozone 4. Sulphur dioxide Which of the above are released into atmosphere due to the burning of crop/biomass residue?

Result
Your answer: —  ·  Correct: D
Explanation

The correct answer is option D (1, 2, 3 and 4).

Biomass burning is a major source of gaseous pollution such as carbon monoxide (CO), methane (CH4), nitrous oxides (NOx) and hydrocarbons in the troposphere[1]. Additionally, greenhouse gas emissions from burning crop residues consist of methane (CH4) and nitrous oxide (N2O) produced by the combustion of crop residues burnt in agricultural fields[2]. Major air pollutants emitted from biomass burning include particulate matters (PM), carbon dioxide (CO2), carbon monoxide (CO), sulfur oxides[3], confirming the release of sulfur dioxide.

Regarding ozone, while it may not be directly emitted during combustion, the burning of biomass releases precursor pollutants like nitrogen oxides and volatile organic compounds that lead to ozone formation in the atmosphere. The question asks about substances "released into atmosphere due to burning," which encompasses both direct emissions and secondary atmospheric products. Therefore, all four pollutants—carbon monoxide, methane, ozone, and sulphur dioxide—are associated with crop/biomass residue burning, making option D the comprehensive and correct answer.

Sources
  1. [2] https://www.fao.org/4/i3671e/i3671e.pdf
  2. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC7597142/
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Q. Consider the following : 1. Carbon monoxide 2. Methane 3. Ozone 4. Sulphur dioxide Which of the above are released into atmosphere d…
At a glance
Origin: Mostly Current Affairs Fairness: Low / Borderline fairness Books / CA: 0/10 · 10/10
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This question stems from the perennial 'Stubble Burning' crisis in North India rather than a static textbook chapter. While scientifically loose (Ozone is technically a secondary pollutant), the question tests your ability to correlate the 'toxic cocktail' of news headlines with basic combustion chemistry. It forces you to prioritize the 'presence' of pollutants over the strict mechanism of their release.

How this question is built

This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.

Statement 1
Is carbon monoxide (CO) emitted into the atmosphere by burning crop or biomass residues?
Origin: Web / Current Affairs Fairness: CA heavy Web-answerable

Web source
Presence: 5/5
"Major air pollutants emitted from biomass burning include particulate matters (PM), carbon dioxide (CO2), carbon monoxide (CO), sulfur oxides ( ..."
Why this source?
  • Explicitly lists CO among the major air pollutants produced by biomass burning.
  • Directly ties biomass burning to emission of carbon monoxide (CO).
Web source
Presence: 5/5
"Biomass burning is a major source of gaseous pollution such as carbon monoxide (CO), methane (CH4), nitrous oxides (NOx) and hydrocarbons in the troposphere"
Why this source?
  • States biomass burning is a major source of gaseous pollution including carbon monoxide (CO).
  • Specifically identifies CO as an emission from biomass burning in the troposphere.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
Strength: 5/5
“Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, grassy and woody plants, residues from agriculture or forestry, oil-rich algae, and the organic component of municipal and industrial wastes. Biomass is a good substitute for the conventional fossil fuels for heating and energy generation purposes. Burning biomass releases about the same amount of carbon dioxide as burning fossil fuels, However, fossil fuels release carbon dioxide captured by photosynthesis over its formative years.”
Why relevant

Says burning biomass releases carbon dioxide and treats biomass as a combustion fuel source, establishing that combustion of biomass emits gaseous carbon species.

How to extend

A student could apply the general rule that incomplete combustion of carbonaceous fuels (biomass) produces CO as well as CO2 and then check combustion chemistry or emission factors for crop-residue fires.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Possible Sources of Brown Carbon are > p. 258
Strength: 4/5
“• r Biomass burning (possibly domestic wood burning) is shown to be a major source of brown carbon. • r Smoke from agricultural fires may be an additional source. • r "Brown carbon" is generally referred to as greenhouse gases and "black carbon" for particulates resulting from impure combustion, such as soot and dust,”
Why relevant

Identifies biomass and agricultural fires as sources of smoke/brown carbon, showing that burning crop/biomass residues produces smoke and combustion byproducts.

How to extend

From 'smoke from agricultural fires' one can infer combustion emissions include gases and particulates; the student could look up typical smoke constituents (including CO) from agricultural burning studies.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) Sulphur > p. 102
Strength: 4/5
“Anthropogenic sourcesl • Forest fires • Combustion of oil, coal, and gas • (c) Formic acid • Biomass burning due to forest fires causes emission of formic acid (HCOOH) and formaldehyde (HCHO) into the atmosphere. • Large fraction of formaldehyde gets oxidation and forms formic acid in the These are three main compounds that cause acidification of rain in the atmosphere. (d) Other Acids: • Chlorine • Phosphoric acid • Hydrochloric acid (smokestacks). • Carbon monoxide and carbon dioxide (automobiles). These become carbonic acid. Re All Rights Reserved. No part of this material may be reproduced in any form or by any means, with out permission in \ riting.”
Why relevant

Discusses biomass burning (forest fires) as a source of volatile combustion products (formaldehyde, formic acid) and separately lists carbon monoxide and dioxide as combustion-related pollutants.

How to extend

A student could generalize that biomass fires emit various carbon-containing gases and therefore consider CO among common combustion pollutants to investigate further.

Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > 1. Air Pollution > p. 38
Strength: 3/5
“The presence in the Earth's atmosphere of man-caused or manmade contaminants which may adversely affect property, or the lives of plants, animals, or humans. Commonly air pollution include carbon dioxide, carbon monoxide, lead, nitrogen oxide, ozone, smoke, and sulphur dioxide. The tremendous increase of vehicles during the last three decades in the country has increased the air pollution, especially in the large cities. Consequently, the urban population is suffering more by cough, nausea, irritation of eyes, and various bronchial and visibility problems. Because of the emission of carbon-dioxide, carbon monoxide, nitrogen oxide, and suspended particles of lead and heavy metals, the urban environment is more polluted than the rural environment.”
Why relevant

Lists carbon monoxide alongside 'smoke' and other combustion-related pollutants, linking CO conceptually to combustion-related air pollution.

How to extend

Using the association of CO with smoke and combustion, a student could compare urban/vehicle emission sources with rural biomass-smoke source profiles to see if CO appears in agricultural fire measurements.

FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Greenhouse Gases(GHGs) > p. 96
Strength: 3/5
“The primary GHGs of concern today are carbon dioxide (CO2 ), Chlorofluorocarbons (CFCs), methane (CH4 ), nitrous oxide (N2O) and ozone (O3 ). Some other gases such as nitric oxide (NO) and carbon monoxide (CO) easily react with GHGs and affect their concentration in the atmosphere. The effectiveness of any given GHG molecule will depend on the magnitude of the increase in its concentration, its life time in the atmosphere and the wavelength of radiation that it absorbs. The chlorofluorocarbons (CFCs) are highly effective. Ozone which absorbs ultra violet radiation in the stratosphere is very effective in absorbing terrestrial radiation when it is present in the lower troposphere.”
Why relevant

Notes that carbon monoxide interacts with greenhouse gases and is present in atmospheric chemistry discussions, implying CO is a relevant combustion-related atmospheric species.

How to extend

A student could use atmospheric chemistry context to look for observational or inventory data on CO from biomass-burning regions to test whether crop-residue burning emits CO.

Statement 2
Is methane (CH4) emitted into the atmosphere by burning crop or biomass residues?
Origin: Web / Current Affairs Fairness: CA heavy Web-answerable

Web source
Presence: 5/5
"Greenhouse gas emissions from burning crop residues consist of methane (CH4) and nitrous oxide (N2O) produced by the combustion of crop residues burnt in agricultural fields."
Why this source?
  • Explicitly states that burning crop residues produces methane (CH4) and nitrous oxide (N2O).
  • Specifically links CH4 emissions to the combustion of crop residues in agricultural fields.
Web source
Presence: 5/5
"Emissions from burning crop residues consist of CH4 and N2O gases produced by the combustion of crop residues burnt on-site, net of removals for animal consumption, decay in the field, and use in other sectors (e.g., biofuel, domestic livestock feed, building materials, etc.)."
Why this source?
  • Reiterates that emissions from burning crop residues consist of CH4 and N2O gases produced by combustion.
  • Notes these emissions come from crop residues burned on-site, directly tying burning to CH4 release.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
Strength: 4/5
“Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, grassy and woody plants, residues from agriculture or forestry, oil-rich algae, and the organic component of municipal and industrial wastes. Biomass is a good substitute for the conventional fossil fuels for heating and energy generation purposes. Burning biomass releases about the same amount of carbon dioxide as burning fossil fuels, However, fossil fuels release carbon dioxide captured by photosynthesis over its formative years.”
Why relevant

States that burning biomass releases greenhouse gas (CO2) and treats biomass burning as a combustion process producing gaseous emissions.

How to extend

A student could combine this with basic combustion chemistry (complete vs incomplete combustion) or emission-factor tables to check whether incomplete combustion of crop residues can produce CH4.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Possible Sources of Brown Carbon are > p. 258
Strength: 4/5
“• r Biomass burning (possibly domestic wood burning) is shown to be a major source of brown carbon. • r Smoke from agricultural fires may be an additional source. • r "Brown carbon" is generally referred to as greenhouse gases and "black carbon" for particulates resulting from impure combustion, such as soot and dust,”
Why relevant

Identifies biomass burning and agricultural fires as major sources of smoke and brown carbon (incomplete combustion products).

How to extend

One could infer that if biomass burning yields incomplete-combustion products (brown carbon, smoke), it may also emit reduced hydrocarbons like CH4 and then look up measurements from agricultural fire studies.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) Sulphur > p. 102
Strength: 3/5
“Anthropogenic sourcesl • Forest fires • Combustion of oil, coal, and gas • (c) Formic acid • Biomass burning due to forest fires causes emission of formic acid (HCOOH) and formaldehyde (HCHO) into the atmosphere. • Large fraction of formaldehyde gets oxidation and forms formic acid in the These are three main compounds that cause acidification of rain in the atmosphere. (d) Other Acids: • Chlorine • Phosphoric acid • Hydrochloric acid (smokestacks). • Carbon monoxide and carbon dioxide (automobiles). These become carbonic acid. Re All Rights Reserved. No part of this material may be reproduced in any form or by any means, with out permission in \ riting.”
Why relevant

Explicitly lists organic species (formaldehyde, formic acid) emitted by biomass burning, indicating that a range of volatile organic compounds result from such burning.

How to extend

Knowing that biomass fires emit volatile organics, a student can reasonably test whether methane is among typical volatile emissions by consulting emission inventories for biomass fires.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > 17,3.3. Methane > p. 256
Strength: 3/5
“• Methane (CH4) is emitted by natural sources such as wetlands, as well as human activities such as leakage from natural gas systems and the raising of livestock. • Natural processes in soil and chemical reactions in the atmosphere help remove CH4 from the atmosphere.”
Why relevant

Provides a concise list of common methane sources (wetlands, natural gas leakage, livestock) but does not list biomass burning among those examples.

How to extend

The omission suggests checking specialized emission/source lists or measurement studies to see if biomass burning is commonly counted as a CH4 source or if it is negligible compared with listed sources.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > CWP & Lifetime of Sreen House Grses: > p. 260
Strength: 2/5
“Carbon dioxide (CO) has a GWP of 1 and serves as a baseline for other GWP values. r The larger the GWP, the more warming the gas causes. For example, methane's 10-year GWP is zrr, *'hiih means that methane will cause zrr times as much warming as an equivalent mass of carbon dioxide over a 10-year time period. • Methane (CH₄) has a GWP more than 20 times higher than CO₂ for a 10-year time scale. CH₄ emitted today lasts for only about 12 years in the atmosphere, on average. However, on a pound-for-pound basis, CH₄ absorbs more energy than CO₂, making its GWP higher. • Nitrous Oxide (N₂O) has a GWP three times that of CO₂ for a 100-year time scale.”
Why relevant

Describes methane's importance as a potent, relatively short-lived GHG, motivating why identifying all CH4 sources (including possible biomass burning) matters for climate impact assessments.

How to extend

A student could use this as rationale to consult GWP-weighted emission inventories and trace whether agricultural/biomass-fire CH4 contributions are included and how large they are.

Statement analysis

This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.

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Statement 3
Is ozone (O3) emitted into the atmosphere by burning crop or biomass residues?
Origin: Web / Current Affairs Fairness: CA heavy Web-answerable

Web source
Presence: 4/5
"Emissions from burning crop residues consist of CH4 and N2O gases produced by the combustion of crop residues burnt on-site,"
Why this source?
  • Explicitly describes emissions from burning crop residues as CH4 and N2O produced by combustion.
  • By specifying the gases emitted (CH4 and N2O) for crop-residue burning, it does not list ozone (O3) as a direct emission.
Web source
Presence: 4/5
"Greenhouse gas emissions from burning crop residues consist of methane (CH4) and nitrous oxide (N2O) produced by the combustion of crop residues burnt in agricultural fields."
Why this source?
  • States greenhouse gas emissions from burning crop residues consist of methane (CH4) and nitrous oxide (N2O).
  • Reinforces that the reported direct emissions from crop-residue burning are CH4 and N2O, with no mention of ozone.
Web source
Presence: 3/5
"Some sources of PM2.5 are directly emitted into the atmosphere. These include black carbon and organic carbon, which are emitted"
Why this source?
  • Describes particulate matter (PM) components — black carbon and organic carbon — as being directly emitted from combustion sources.
  • Shows typical combustion emissions include PM and carbonaceous species rather than listing ozone as a direct combustion emission.

Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > ozone depletion > p. 11
Strength: 5/5
“Ozone is a form of oxygen in which three atoms of oxygen combine to form a single molecule of ozone. Ozone normally is not abundant in the lower atmosphere under natural conditions. It does, however, form in smog by the action of sunlight on oxides of nitrogen and organic compounds. Tis ozone does not stay in the air for very long. It reacts with other gases in the atmosphere and changes to normal oxygen molecules. Ozone exists in the stratosphere, though the total amount is small. It is concentrated in a layer between 20 and 50 kilometres. Te ozone is continually formed and then removed.”
Why relevant

States that ground‑level ozone forms in smog by the action of sunlight on oxides of nitrogen (NOx) and organic compounds.

How to extend

A student could check whether biomass burning emits NOx and reactive organic gases; if so, those emissions + sunlight could produce ozone rather than ozone being directly emitted.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Ozone. > p. 64
Strength: 4/5
“. It occurs naturally in the upper layers of the atmosphere. • o This important gas shields the earth from the harmful ultraviolet rays of the sun, • r However, at the ground level, it is a pollutant with highly toxic effects. • o Vehicles and industries are the major source of ground-level ozone emissions. • . Ozone makes our eyes itch, burn, and water. It lowers our resistance to cold and pneumonia. • r Nitrogen oxide (Nox) • . It causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal”
Why relevant

Says ground‑level ozone is a pollutant produced in relation to vehicle/industry emissions and cites nitrogen oxides (NOx) from burning fuels as a cause.

How to extend

Compare the combustion chemistry of crop/biomass burning to fuel combustion to see if similar NOx and organics are produced that can generate ozone photochemically.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) Sulphur > p. 102
Strength: 4/5
“Anthropogenic sourcesl • Forest fires • Combustion of oil, coal, and gas • (c) Formic acid • Biomass burning due to forest fires causes emission of formic acid (HCOOH) and formaldehyde (HCHO) into the atmosphere. • Large fraction of formaldehyde gets oxidation and forms formic acid in the These are three main compounds that cause acidification of rain in the atmosphere. (d) Other Acids: • Chlorine • Phosphoric acid • Hydrochloric acid (smokestacks). • Carbon monoxide and carbon dioxide (automobiles). These become carbonic acid. Re All Rights Reserved. No part of this material may be reproduced in any form or by any means, with out permission in \ riting.”
Why relevant

Notes that biomass burning (e.g., forest fires) emits volatile organic compounds such as formaldehyde and formic acid into the atmosphere.

How to extend

Use the fact that organic compounds are ozone precursors: if crop/biomass burning emits these VOCs, they could react (with NOx and sunlight) to form ozone locally.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
Strength: 3/5
“Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, grassy and woody plants, residues from agriculture or forestry, oil-rich algae, and the organic component of municipal and industrial wastes. Biomass is a good substitute for the conventional fossil fuels for heating and energy generation purposes. Burning biomass releases about the same amount of carbon dioxide as burning fossil fuels, However, fossil fuels release carbon dioxide captured by photosynthesis over its formative years.”
Why relevant

Explains that burning biomass releases combustion products similar to fossil fuels (e.g., CO2), implying combustion processes emit various gases.

How to extend

Infer that because biomass combustion is a combustion process, it may also emit NOx and VOCs—check emission studies to see if those precursors are present to enable ozone formation.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 19: Ozone Depletion > Effects on air quatity > p. 272
Strength: 3/5
“Reduction in stratospheric ozone and the concomitant increase in UV-B radiation penetrating to the lower atmosphere result in higher photo dissociation rates of key trace gases that control the chemical reactivity of the troposphere. • This can increase both production and destruction of ozone (Ofi) and related oxidants such as hydrogen peroxide (H〈O,〉), which are known to have adverse effects on human health, terrestrial plants, and outdoor materials. • Changes in the atmospheric concentrations of the hydroxyl radical (OH) may change the atmospheric lifetimes of climatically important gases such as methane (CHfi) and the CFC substitutes.”
Why relevant

Describes that changes in concentrations of reactive species affect both production and destruction of ozone and related oxidants in the troposphere.

How to extend

A student could infer that adding combustion-derived reactive gases from biomass burning could shift local chemistry toward net ozone production under sunlight.

Statement analysis

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Statement 4
Is sulphur dioxide (SO2) emitted into the atmosphere by burning crop or biomass residues?
Origin: Web / Current Affairs Fairness: CA heavy Web-answerable

Web source
Presence: 5/5
"Emissions from burning crop residues consist of CH4 and N2O gases produced by the combustion of crop residues burnt on-site,"
Why this source?
  • Directly addresses burning of crop residues and lists which gases are emitted from that activity.
  • Specifies emissions from burning crop residues consist of CH4 and N2O, not SO2, implying SO2 is not reported for that source in this dataset.
Web source
Presence: 3/5
"Important examples of air pollutants are carbon monoxide, chlorofluorocarbons, ammonia, nitrogen oxides, sulphur dioxide and volatile organic compounds."
Why this source?
  • Identifies sulphur dioxide as an air pollutant associated with industrial and agricultural activities generally.
  • Does not, however, link sulphur dioxide specifically to burning crop or biomass residues.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > b) Sulphur Cycle > p. 21
Strength: 5/5
“Atmospheric hydrogen sulphide also gets oxidised into sulphur dioxide. Atmospheric sulphur dioxide is carried back to the earth after being dissolved in rainwater as weak sulphuric acid. Whatever the source, sulphur in the form of suiphates is take up by plants and incorporated through a series of metabolic processes into sulphur bearing amino acid which is incorporated in the proteins of autotroph tissues. It then passes through the grazing food chain. Sulphur bound in living organism is carried back to the soil, to the bottom of ponds and lakes and seas through excretion and decomposition of dead organic material. The Bio-geochemical cycles discussed here are only a few of the many cycles present in the ecosystem.”
Why relevant

Shows sulphur in the environment is cycled through living matter and that atmospheric H2S can oxidize into SO2.

How to extend

A student could infer that if plants/biomass contain sulphur, combustion or oxidation of that biomass could produce SO2.

Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > 20.1. Composition of The Earth's Atmosphere > p. 270
Strength: 4/5
“• The composition of Earth's atmosphere is largely governed by the by-products of the life it sustains. Dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon and traces of hydrogen, helium, and other noble gases. The remaining gases are often referred to as trace gases, among which are the greenhouse gases, principally carbon dioxide (0.036%), methane, nitrous oxide, and ozone.• Various industrial pollutants also may be present as gases or aerosols, such as chlorine, fluorine compounds and elemental mercury vapour. Sulphur compounds such as hydrogen sulphide (H2S) and sulphur dioxide (SO2) may be derived from natural sources or industrial air pollution.”
Why relevant

States sulphur compounds such as H2S and SO2 may be derived from natural sources as well as industrial pollution.

How to extend

Use the idea that natural/biological sources can yield SO2 to consider biomass burning as a plausible natural/anthropogenic source.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) Sulphur > p. 102
Strength: 4/5
“Anthropogenic sourcesl • Forest fires • Combustion of oil, coal, and gas • (c) Formic acid • Biomass burning due to forest fires causes emission of formic acid (HCOOH) and formaldehyde (HCHO) into the atmosphere. • Large fraction of formaldehyde gets oxidation and forms formic acid in the These are three main compounds that cause acidification of rain in the atmosphere. (d) Other Acids: • Chlorine • Phosphoric acid • Hydrochloric acid (smokestacks). • Carbon monoxide and carbon dioxide (automobiles). These become carbonic acid. Re All Rights Reserved. No part of this material may be reproduced in any form or by any means, with out permission in \ riting.”
Why relevant

Lists biomass/forest burning among anthropogenic sources of atmospheric compounds (in context of acids and oxidation products emitted by combustion).

How to extend

Combine this with knowledge that combustion oxidizes sulphur to SO2 to test whether biomass firing emits SO2.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
Strength: 3/5
“Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities. It is derived from numerous sources, including the by-products from the timber industry, agricultural crops, grassy and woody plants, residues from agriculture or forestry, oil-rich algae, and the organic component of municipal and industrial wastes. Biomass is a good substitute for the conventional fossil fuels for heating and energy generation purposes. Burning biomass releases about the same amount of carbon dioxide as burning fossil fuels, However, fossil fuels release carbon dioxide captured by photosynthesis over its formative years.”
Why relevant

Describes biomass as carbonaceous waste burned for energy, noting burning biomass releases combustion products similar to fossil fuels.

How to extend

By analogy to fossil fuels (which release SO2 when containing sulphur), a student could check sulphur content of crop residues to judge SO2 emissions.

Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Possible Sources of Brown Carbon are > p. 258
Strength: 3/5
“• r Biomass burning (possibly domestic wood burning) is shown to be a major source of brown carbon. • r Smoke from agricultural fires may be an additional source. • r "Brown carbon" is generally referred to as greenhouse gases and "black carbon" for particulates resulting from impure combustion, such as soot and dust,”
Why relevant

Identifies biomass burning and agricultural fires as significant sources of atmospheric smoke and carbonaceous pollutants.

How to extend

Use this pattern (biomass burning emits gaseous/particulate pollutants) to investigate whether SO2 is among those emitted from agricultural residue fires.

Statement analysis

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Pattern takeaway: UPSC Environment questions often conflate 'Direct Emission' with 'Immediate Resultant Presence'. If a process triggers the formation of a pollutant (like Ozone via NOx/VOCs) in the immediate vicinity, UPSC tends to count it as 'released' in multiple-choice scenarios.
How you should have studied
  1. [THE VERDICT]: Trap/Forced Choice. Standard books (Shankar/NCERT) classify Ozone as secondary, but the options force you to select it. This is an 'Applied Science' question.
  2. [THE CONCEPTUAL TRIGGER]: Air Pollution > Stubble Burning (Winter Pollution). The specific mix of gases mentioned mirrors the 'Delhi Smog' analysis found in The Hindu/Indian Express explainers.
  3. [THE HORIZONTAL EXPANSION]: Memorize the 8 pollutants in the National Air Quality Index (AQI): PM10, PM2.5, NO2, SO2, CO, O3, NH3, Pb. Contrast this with the 12 pollutants under NAAQS. Study 'Short-Lived Climate Pollutants' (SLCPs): Black Carbon, Methane, Tropospheric Ozone, HFCs.
  4. [THE STRATEGIC METACOGNITION]: Do not be a rigid scientist. If you know for a fact that Biomass (Organic matter) contains Carbon, Hydrogen, and Sulphur, then CO (1), Methane (2), and SO2 (4) are inevitable. Since no option exists for '1, 2, and 4 only', you must accept the superset [D].
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Concept hooks from this question
📌 Adjacent topic to master
S1
👉 Biomass burning as a source of carbonaceous particulate (brown/black carbon)
💡 The insight

Biomass burning is a major source of brown carbon and produces soot-like particulates that affect atmospheric radiative properties.

High-yield for questions on air pollution and climate forcing; links agricultural/forest fires to particulate emissions, health impacts, and short-term climate effects, enabling answers on mitigation and policy trade-offs.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Possible Sources of Brown Carbon are > p. 258
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > 4. Black carbon and climate change > p. 14
🔗 Anchor: "Is carbon monoxide (CO) emitted into the atmosphere by burning crop or biomass r..."
📌 Adjacent topic to master
S1
👉 Carbon dioxide versus carbon monoxide in atmospheric chemistry
💡 The insight

Carbon dioxide is the primary atmospheric carbon form in the carbon cycle, while carbon monoxide interacts with greenhouse gases and alters atmospheric chemistry.

Essential for distinguishing greenhouse-gas focus (CO2) from reactive trace gases (CO) in climate and air-quality questions; connects carbon cycle concepts to emissions accounting and atmospheric reaction pathways.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > L) The Carbon Cycle > p. 19
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Greenhouse Gases(GHGs) > p. 96
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > 12.3.2 Carbon Dioxide > p. 255
🔗 Anchor: "Is carbon monoxide (CO) emitted into the atmosphere by burning crop or biomass r..."
📌 Adjacent topic to master
S1
👉 Combustion of biomass releases CO2 comparable to fossil fuels
💡 The insight

Burning biomass releases roughly similar amounts of carbon dioxide as burning fossil fuels.

Important for debates on bioenergy, carbon neutrality and lifecycle emissions; helps answer questions comparing renewable energy options, emission inventories, and policy implications for biomass use.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
🔗 Anchor: "Is carbon monoxide (CO) emitted into the atmosphere by burning crop or biomass r..."
📌 Adjacent topic to master
S2
👉 Sources of Methane: Natural vs Anthropogenic
💡 The insight

Methane has both natural origins (e.g., wetlands) and human origins (e.g., livestock, fossil fuel leakage).

High-yield for climate-change questions that ask to attribute greenhouse-gas emissions by source. Mastering this helps answer policy and mitigation questions linking agriculture, energy, and emissions inventories.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > 17,3.3. Methane > p. 256
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 7: Climate Change > 2. greenhouse gases > p. 11
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Greenhouse Gases(GHGs) > p. 96
🔗 Anchor: "Is methane (CH4) emitted into the atmosphere by burning crop or biomass residues..."
📌 Adjacent topic to master
S2
👉 Biomass Burning and Atmospheric Pollutants
💡 The insight

Burning biomass or agricultural residues emits carbonaceous pollutants and gases such as CO2, brown carbon, formaldehyde and formic acid.

Crucial for questions on air pollution, rural practices, and mitigation trade-offs; links agriculture, renewable energy (biomass), and atmospheric chemistry topics frequently tested in environment sections.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 22: Renewable Energy > 22.6 BIOMASS > p. 292
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) Sulphur > p. 102
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Possible Sources of Brown Carbon are > p. 258
🔗 Anchor: "Is methane (CH4) emitted into the atmosphere by burning crop or biomass residues..."
📌 Adjacent topic to master
S2
👉 Greenhouse Gas Global Warming Potential (GWP) and Atmospheric Lifetime
💡 The insight

Different greenhouse gases have different GWPs and lifetimes; methane has a substantially higher short-term GWP and a shorter atmospheric lifetime.

Essential for evaluating the climate impact of specific gases, designing mitigation priorities, and answering comparative questions on gas-specific policy measures and timelines.

📚 Reading List :
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > CWP & Lifetime of Sreen House Grses: > p. 260
  • FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 11: World Climate and Climate Change > Greenhouse Gases(GHGs) > p. 96
🔗 Anchor: "Is methane (CH4) emitted into the atmosphere by burning crop or biomass residues..."
📌 Adjacent topic to master
S3
👉 Tropospheric ozone forms from NOx and VOCs (photochemical ozone)
💡 The insight

Ground‑level ozone is produced by sunlight-driven reactions of nitrogen oxides and organic compounds, not emitted as O3 directly from combustion.

High-yield for UPSC: distinguishes direct pollutant emissions from secondary pollutant formation, links air‑quality questions (smog, health impacts) with source control (NOx/VOC reduction). Enables answering questions on why controlling precursors matters and on differences between primary and secondary pollutants.

📚 Reading List :
  • Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > ozone depletion > p. 11
  • Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Ozone. > p. 64
🔗 Anchor: "Is ozone (O3) emitted into the atmosphere by burning crop or biomass residues?"
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🌑 The Hidden Trap

Peroxyacetyl Nitrate (PAN). It is the 'sibling' of Ozone in Photochemical Smog. It causes the characteristic eye irritation during smog events. If UPSC asks about secondary pollutants from burning again, PAN is the next logical target.

⚡ Elimination Cheat Code

The 'Elemental Audit' Hack. Biomass is organic matter = Carbon + Hydrogen + Sulphur + Nitrogen. Burning it implies oxidation. C becomes CO/CO2 (Statement 1). H becomes Hydrocarbons/Methane (Statement 2). S becomes SO2 (Statement 4). Since 1, 2, and 4 are chemically guaranteed and no option matches '1, 2, 4', the only valid choice is [D].

🔗 Mains Connection

Link this to GS3 (Agriculture & Economy): The 'Stubble Burning' issue is a failure of the 'Market for Crop Residue'. Connect it to solutions like 'Torrefaction' (converting stubble to coal-like pellets) and the 'Pusa Bio-Decomposer'.

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SIMILAR QUESTIONS

IAS · 2022 · Q10 Relevance score: 5.00

Consider the following : 1. Carbon monoxide 2. Nitrogen oxide 3. Ozone 4. Sulphur dioxide Excess of which of the above in the environment is/are cause(s) of acid rain ?

IAS · 2011 · Q2 Relevance score: 2.48

Consider the following: 1. Carbon dioxide 2. Oxides of Nitrogen 3. Oxides of Sulphur Which of the above is/ are the emission/ emissions from coal combustio nat thermal power plants ?

IAS · 2016 · Q86 Relevance score: 2.02

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.

IAS · 2014 · Q24 Relevance score: 0.20

Which of the following are some important pollutants released by steel industry in India? 1. Oxides of sulphur 2. Oxides of nitrogen 3. Carbon monoxide 4. Carbon dioxide Select the correct answer using the code given below.

IAS · 2010 · Q37 Relevance score: -0.63

Consider the following: 1. Oxides of Hydrogen 2. Oxides of Nitrogen 3. Oxides of Sulphur Which of the above causes/cause acid rain ?