Question map
Consider the following statements : 1. Coal ash contains arsenic, lead and mercury. 2. Coal-fired power plants release sulphur dioxide and oxides of nitrogen into the environment. 3. High ash content is observed in Indian coal. Which of the statements given above is/are correct ?
Explanation
The correct answer is Option 4 (1, 2 and 3) because all three statements accurately describe the environmental and physical characteristics of coal and its combustion in India.
- Statement 1 is correct: Coal ash (fly ash) is a byproduct containing heavy metals such as arsenic, lead, mercury, and cadmium. These toxic substances can leach into groundwater or become airborne, posing significant health risks.
- Statement 2 is correct: The combustion of coal releases gaseous pollutants. Sulphur present in coal oxidizes to sulphur dioxide (SO2), while high combustion temperatures cause atmospheric nitrogen to form oxides of nitrogen (NOx), both of which contribute to acid rain and smog.
- Statement 3 is correct: Indian coal is known for its high ash content (often 35% to 45%), which is significantly higher than the global average. This makes it lower in calorific value and necessitates extensive pollution control measures.
Since all statements are scientifically and geographically factual, Option 4 is the comprehensive choice.
PROVENANCE & STUDY PATTERN
Full viewThis is a classic 'Intersection Question' where Geography (Coal resources) meets Environment (Pollution). Statements 2 and 3 are standard textbook facts found in NCERT and Majid Husain. Statement 1 is a logical extension: if coal is a 'dirty' fossil fuel dug from the earth, its residue (ash) inevitably concentrates crustal impurities like heavy metals.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Explicitly lists mercury, arsenic and lead among 'toxic trace elements' released from power plants via coal ash.
- Directly ties those elements to disposal and dispersal of coal ash, answering whether coal ash contains them.
- States that coal flyash tends to have higher concentrations of mercury, providing specific evidence for mercury in coal ash.
- Gives an estimated average mercury concentration in Indian coal ash, supporting the claim for mercury presence.
Defines fly ash as the fine residue produced when solid fuel combustion occurs and distinguishes it from bottom ash.
A student can infer that any elements present in coal may be partitioned into fly ash during combustion and then check external sources for which trace elements typically occur in coal/ash (e.g., arsenic, lead, mercury).
States that Indian coal contains a substantial percentage of ash (20–30%), showing that coal inherently contains noncombustible mineral matter.
Given high ash content, a student could reasonably expect minerals and associated trace elements to be present in the ash and then look up common trace metals associated with coal mineral matter.
Gives examples of coals with very high ash fractions (e.g., 35% ash), reinforcing that combustion yields significant residual ash from coal.
High ash fractions make it plausible that trace constituents in the original coal will be concentrated in the ash; a student can use that to justify checking analytical data on ash composition for specific metals.
Explains coal types and notes lower-rank coals (lignite) have high ash content, indicating variability in ash-producing potential among coals.
A student can combine this with knowledge of coal type distribution to predict which ashes are more likely to concentrate impurities and then consult chemical analyses for those ashes.
Notes health effects (pneumoconiosis) from coal dust exposure, implying coal and its residues can carry harmful substances affecting health.
While not naming metals, this suggests coal-related materials can be hazardous; a student could therefore reasonably investigate whether toxic elements (like arsenic, lead, mercury) are among those hazards in ash.
- Explicitly lists Sulphur Oxides and Nitrogen Oxides and names thermal power plants as a source.
- Links these pollutants to health impacts, implying their emission from coal/thermal operations.
- States that fuels such as coal contain sulphur and nitrogen.
- Explains that combustion of such fuels produces oxides of sulphur and nitrogen.
- Explicitly associates Nitrogen Oxide and Sulphur Oxide with thermal power plants, industries and vehicles.
- Describes health effects of these oxides, reinforcing that they are emitted pollutants from such sources.
- Direct general statement that Indian coal contains about 20–30% ash.
- Frames Indian coal as 'relatively inferior' tied to high ash proportion.
- Gives a concrete example (Ramgarh coal) with a high ash proportion (~30%).
- Demonstrates that high ash is present in specific Indian coalfields, not just a theoretical claim.
- Provides another field-level figure (Deogarh coal ~35% ash) showing even higher ash in places.
- Supports the pattern of substantial ash content across Indian coal deposits.
- [THE VERDICT]: Sitter. Statements 2 and 3 are direct hits from standard texts (Shankar/Majid Husain). Statement 1 is a 'General Science' inference manageable with common sense.
- [THE CONCEPTUAL TRIGGER]: The 'Life Cycle of Coal' theme: Extraction (Geography) → Combustion (Chemistry) → Waste/Pollution (Environment).
- [THE HORIZONTAL EXPANSION]: Memorize the 'Coal Profile': 1) Indian Coal (Gondwana) = High Ash (30-45%), Low Sulphur. 2) Tertiary Coal (Assam/J&K) = Low Ash, High Sulphur. 3) Fly Ash Composition = Silica (SiO2), Alumina (Al2O3), Calcium (CaO) + Trace Toxics (As, Pb, Hg, Cd). 4) Flue Gas Desulphurization (FGD) removes SO2.
- [THE STRATEGIC METACOGNITION]: When studying a major resource like Coal, do not stop at distribution maps. You must map its 'Negative Externalities'. Ask: What comes OUT of the chimney? (SOx, NOx, Hg). What is left at the BOTTOM? (Ash with heavy metals). UPSC tests the *consequences* of resource use.
Ash content quantifies the mineral residue remaining after coal combustion and determines the volume of coal ash produced.
High-yield for UPSC questions on energy and environment because ash percentages affect power-plant waste management, pollution load, and resource quality. Connects to topics on thermal power generation, industrial pollution, and waste disposal policy; useful for questions asking impacts of fuel quality and mitigation strategies.
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 9: Distribution of World Natural Resources > 2. High ash content > p. 11
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 8: Energy Resources > Source: Provisional Coal Statistics 2016–17, Coal Controller's Organization, Kolkata. > p. 5
- Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 27: Fuel and Power > Types of coal > p. 265
Fly ash is the fine particulate that rises with combustion gases while bottom ash remains as heavier residue, affecting dispersion and exposure pathways.
Important for answering questions on air pollution, ash management, and environmental fate of combustion residues. Links to atmospheric transport, solid waste handling, and urban/rural exposure issues; enables analysis of mitigation measures like electrostatic precipitators and ash ponds.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.2.4. Fly Ash > p. 66
Inhalation of coal dust and fine ash particles causes occupational respiratory disease, illustrating direct human health consequences of coal combustion residues.
Clinches answers on public health and occupational hazards in environment sections of UPSC mains and ethics. Connects occupational health policy, industrial regulation, and environmental health interventions; useful for case-based questions on miner welfare and pollution control.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > e) Pneumoconiosis > p. 416
Burning coal releases the sulphur and nitrogen it contains, forming sulphur dioxide and nitrogen oxides.
High-yield for environment and pollution questions: explains the fundamental chemical origin of major air pollutants and links to industrial energy use. Connects to topics on air quality, industrial emissions regulation, and pollution mitigation measures; useful for questions on causes and control of air pollution.
- Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Activity 4.4 > p. 70
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > b) Sulphur Cycle > p. 21
Coal/thermal power plants are repeatedly identified as direct emitters of SOx and NOx into the atmosphere.
Essential for policy and geography essays and prelims/GS: helps identify sectors targeted by emission standards and technology interventions (e.g., flue gas treatment). Links to energy policy, environmental law, and public health question patterns.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Fly ash notification zozr > p. 67
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Consequences of Air Pollution > p. 40
Sulphur dioxide and nitrogen oxides form acids in the atmosphere and cause respiratory and eye irritation.
High relevance for environmental impact and disaster risk topics: explains downstream ecological and human-health consequences, useful for questions on acid rain, ecosystem damage, and public health interventions.
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Acidification > p. 8
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Fly ash notification zozr > p. 67
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Consequences of Air Pollution > p. 40
Ash percentage is a primary measure of coal quality and directly determines whether coal is 'high ash'.
High-yield for UPSC geography and environment questions because these metrics determine industrial uses, pollution implications, and energy value; links to topics on power generation, pollution (fly ash) and resource quality; enables answering questions on coal suitability and impacts.
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 9: Distribution of World Natural Resources > 2. High ash content > p. 11
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 8: Energy Resources > Source: Provisional Coal Statistics 2016–17, Coal Controller's Organization, Kolkata. > p. 5
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 8: Energy Resources > COAL DEPOSITS OF THE TERTIARY PERIOD > p. 6
The 'Sulphur Trap': While Indian coal has High Ash, it typically has LOW Sulphur content compared to international standards. However, because we burn so much of it, our aggregate SO2 emissions are massive. Expect a statement swapping these properties: 'Indian coal is characterized by low ash and high sulphur' (False).
The 'Dirty Earth' Heuristic: Coal is fossilized organic matter mixed with soil/rock. Soil contains trace heavy metals. Therefore, 'Coal ash contains [List of common heavy metals]' is almost certainly TRUE. Unless the option lists something absurd like 'Plutonium' or 'Gold', accept that fossil fuel waste contains trace toxins.
Mains GS3 (Energy vs Environment): High ash content means lower Calorific Value → more coal burned for same electricity → higher emissions. This connects to the 'Washery' policy (washing coal to reduce ash) and the logistical burden on Indian Railways (transporting ash-heavy coal).