Pollution Archives

31. With reference to ‘fly ash’ produced by the power plants using coal as

With reference to ‘fly ash’ produced by the power plants using coal as fuel, which of the following statements is/are correct?

1. Fly ash can be used in the production of bricks for building construction.
2. Fly ash can be used as a replacement for some of the Portland cement contents of concrete.
3. Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements.

Select the correct answer using the code given below.

1 and 2

2 only

1 and 3

3 only

This question was previously asked in

UPSC IAS – 2015

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Statements 1 and 2 are correct regarding the uses of fly ash produced by power plants. Statement 3 is incorrect as fly ash contains more than just silicon dioxide and calcium oxide, and it can contain toxic elements.

Fly ash is a valuable by-product with established applications in construction materials. It is commonly used in manufacturing bricks and as a partial replacement for Portland cement in concrete mixes, improving properties like strength and durability. However, fly ash contains various metal oxides and trace elements, some of which can be toxic.

Fly ash typically consists primarily of silicon dioxide (SiO₂), aluminium oxide (Al₂O₃), iron oxide (Fe₂O₃), and calcium oxide (CaO). It also contains smaller amounts of magnesium oxide (MgO), titanium dioxide (TiO₂), sulphur trioxide (SO₃), and trace amounts of other elements, including heavy metals like arsenic, mercury, and lead, depending on the source of coal and combustion conditions. Its utilization helps in waste management and environmental protection by reducing the need for conventional materials and preventing landfilling.

32. What can be the impact of excessive/inappropriate use of nitrogenous f

What can be the impact of excessive/inappropriate use of nitrogenous fertilizers in agriculture?

1. Proliferation of nitrogen-fixing microorganisms in soil can occur.
2. Increase in the acidity of soil can take place.
3. Leaching of nitrate to the ground-water can occur.

Select the correct answer using the code given below.

1 and 3 only

2 only

2 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2015

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Statements 2 and 3 are correct regarding the impact of excessive/inappropriate use of nitrogenous fertilizers in agriculture.

Excessive use of nitrogenous fertilizers can lead to soil degradation and environmental pollution. The process of nitrification, where ammonium from fertilizers is converted to nitrate, releases hydrogen ions, increasing soil acidity over time (Statement 2 is correct). Nitrate is highly soluble and mobile in soil, making it susceptible to leaching into groundwater, causing contamination and potential health risks (Statement 3 is correct).

Statement 1 is generally incorrect. Excessive nitrogen supply from fertilizers often suppresses the activity of symbiotic nitrogen-fixing microorganisms (like Rhizobium associated with legumes) because the plant can easily access nitrogen from the soil and reduces the need to support nitrogen fixation. Proliferation of non-fixing microbes might occur, but not specifically nitrogen-fixing ones due to direct fertilizer use.

33. There is some concern regarding the nanoparticles of some chemical ele

There is some concern regarding the nanoparticles of some chemical elements that are used by the industry in the manufacture of various products. Why?

They can accumulate in the environment, and contaminate water and soil.
They can enter the food chains.
They can trigger the production of free radicals.

Select the correct answer using the code given below.

1 and 2 only

3 only

1 and 3 only

1, 2 and 3

This question was previously asked in

UPSC IAS – 2014

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All three statements express valid concerns regarding the use and potential environmental and health impacts of nanoparticles. Their small size allows them to easily interact with biological systems and the environment in ways that larger particles do not.

Statement 1 is correct. Due to their extremely small size and high surface area, nanoparticles are highly mobile and can persist and accumulate in various environmental compartments like water and soil, leading to contamination.
Statement 2 is correct. Nanoparticles can be taken up by organisms (plants, animals, microorganisms) from contaminated environments and can then transfer through trophic levels, entering the food chain.
Statement 3 is correct. Many types of nanoparticles, particularly metal and metal oxide nanoparticles, have been shown to trigger the production of reactive oxygen species (ROS) or free radicals in biological systems. This can cause oxidative stress, leading to cell damage, inflammation, and potentially other adverse health effects.

Nanoparticles are increasingly used in various industrial products (cosmetics, paints, electronics, textiles, medicine, etc.). While nanotechnology offers significant benefits, the potential risks associated with the environmental fate, persistence, and toxicity of engineered nanoparticles are subjects of ongoing research and regulatory concern.

34. Which of the following are some important pollutants released by steel

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.

1, 3 and 4 only

2 and 3 only

1 and 4 only

1, 2, 3 and 4

This question was previously asked in

UPSC IAS – 2014

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Steel industry processes are significant sources of various air pollutants, including oxides of sulphur, oxides of nitrogen, carbon monoxide, and carbon dioxide.

Oxides of sulphur (SOx) and nitrogen (NOx) are produced during the combustion of fuels and from raw materials containing sulphur and nitrogen. Carbon monoxide (CO) is a product of incomplete combustion. Carbon dioxide (CO2) is produced from the combustion of carbon-based fuels (like coal or coke) and also from chemical reactions involved in steel production (e.g., reduction of iron oxides). All four listed pollutants are associated with steel manufacturing.

Steel plants also release particulate matter, volatile organic compounds (VOCs), and heavy metals. Controlling these emissions is a major environmental challenge for the industry.

35. Brominated flame retardants are used in many household products like m

Brominated flame retardants are used in many household products like mattresses and upholstery. Why is there some concern about their use?

1. They are highly resistant to degradation in the environment.
2. They are able to accumulate in humans and animals.

Select the correct answer using the code given below.

1 only

2 only

Both 1 and 2

Neither 1 nor 2

This question was previously asked in

UPSC IAS – 2014

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The concern about brominated flame retardants (BFRs) stems from their environmental persistence and their ability to bioaccumulate in living organisms, including humans and animals.

Brominated flame retardants are persistent organic pollutants (POPs) or candidates for this classification. POPs are chemicals that remain intact in the environment for long periods, become widely distributed geographically, accumulate in the fatty tissue of humans and wildlife, and have harmful impacts on human health or the environment.

Some BFRs, such as certain polybrominated diphenyl ethers (PBDEs), have been phased out or restricted in many countries due to concerns about their toxicity, persistence, and bioaccumulation potential. Exposure to BFRs has been linked to potential adverse health effects, including effects on the endocrine system, neurological development, and reproductive health.

36. Photochemical smog is a resultant of the reaction among

Photochemical smog is a resultant of the reaction among

NO₂, O₃ and peroxyacetyl nitrate in the presence of sunlight

CO, O₂ and peroxyacetyl nitrate in the presence of sunlight

CO, CO₂ and NO₂ at low temperature

high concentration of NO₂, O₃ and CO in the evening

This question was previously asked in

UPSC IAS – 2013

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Photochemical smog is a complex mixture of air pollutants that forms when sunlight reacts with certain chemicals in the atmosphere. Key components and precursors include nitrogen oxides (NOx) and volatile organic compounds (VOCs). The resulting smog contains pollutants like ozone (O₃), peroxyacetyl nitrate (PAN), and aldehydes.

The formation of photochemical smog is driven by sunlight. Nitrogen dioxide (NO₂) is a primary pollutant that photodissociates in sunlight to form nitric oxide (NO) and atomic oxygen (O). This atomic oxygen quickly reacts with molecular oxygen (O₂) to form ozone (O₃). VOCs react with NOx and other atmospheric components in the presence of sunlight to form a variety of secondary pollutants, including PAN. Therefore, NO₂, O₃ (as a product), and PAN (as a product), with sunlight as the driving force, are central to photochemical smog.

Photochemical smog is often referred to as “Los Angeles smog” because it was first recognized in Los Angeles. It differs from traditional “London smog” (sulfurous smog), which is caused by the burning of fossil fuels containing sulfur and occurs under cool, humid conditions. Photochemical smog is more common in sunny, dry climates with significant vehicular traffic.

37. Acid rain is caused by the pollution of environment by

Acid rain is caused by the pollution of environment by

carbon dioxide and nitrogen

carbon monoxide and carbon dioxide

ozone and carbon dioxide

nitrous oxide and sulphur dioxide

This question was previously asked in

UPSC IAS – 2013

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The correct answer is D) nitrous oxide and sulphur dioxide.

Acid rain is primarily caused by atmospheric pollutants, mainly sulfur dioxide (SO₂) and nitrogen oxides (NOx). These gases are released into the atmosphere, primarily from the burning of fossil fuels. In the atmosphere, they react with water, oxygen, and other chemicals to form sulfuric and nitric acids. These acids then fall to the Earth’s surface through rain, snow, fog, or dry deposition. While the term “nitrous oxide” (N₂O) is specifically mentioned in the option, it is one of the nitrogen oxides (NOx) group, although NO and NO₂ from combustion are the main contributors to acid rain’s nitrogen component. However, compared to other options which list substances not responsible for acid rain (Carbon dioxide, Carbon monoxide, Ozone, Nitrogen), this option correctly identifies the two major categories of pollutants that lead to acid rain (sulfur compounds and nitrogen compounds).

Sulfur dioxide emissions largely come from power plants and industrial facilities burning coal and oil. Nitrogen oxide emissions come from vehicle exhausts, power plants, and industrial combustion. Acid rain has harmful effects on ecosystems, damaging forests, lakes, buildings, and monuments.

38. Due to improper/indiscriminate disposal of old and used computers or t

Due to improper/indiscriminate disposal of old and used computers or their parts, which of the following are released into the environment as e-waste?

1. Beryllium

2. Cadmium

3. Chromium

4. Heptachlor

5. Mercury

6. Lead

7. Plutonium

Select the correct answer using the codes given below.

1, 3, 4, 6 and 7 only

1, 2, 3, 5 and 6 only

2, 4, 5 and 7 only

1, 2, 3, 4, 5, 6 and 7

This question was previously asked in

UPSC IAS – 2013

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The correct answer is B) 1, 2, 3, 5 and 6 only.

Electronic waste (e-waste), such as old computers and their parts, contains various hazardous substances. The list provided includes several heavy metals commonly found in electronic components: Beryllium (1), Cadmium (2), Chromium (3, often hexavalent chromium), Mercury (5), and Lead (6). These substances pose significant environmental and health risks if not disposed of properly. Heptachlor (4) is an organochlorine pesticide, not a standard component of electronics. Plutonium (7) is a radioactive element associated with nuclear materials, not found in typical consumer electronics. Therefore, 1, 2, 3, 5, and 6 are commonly released into the environment from improper e-waste handling.

Other hazardous substances found in e-waste include brominated flame retardants (BFRs), polychlorinated biphenyls (PCBs – in older equipment), and various other chemicals in plastics and circuit boards. Proper e-waste management involves recycling and safe disposal methods to prevent these toxins from contaminating soil, water, and air.

39. Which of the following can be found as pollutants in the drinking wate

Which of the following can be found as pollutants in the drinking water in some parts of India?

1. Arsenic
2. Sorbitol
3. Fluoride
4. Formaldehyde
5. Uranium

Select the correct answer using the codes given below.

1 and 3 only

2, 4 and 5 only

1, 3 and 5 only

1, 2, 3, 4 and 5

This question was previously asked in

UPSC IAS – 2013

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Arsenic, Fluoride, and Uranium are well-documented as pollutants found in drinking water sources in various parts of India, often occurring naturally at harmful concentrations.

1. Arsenic: Widespread arsenic contamination of groundwater is a major public health issue in states like West Bengal, Bihar, Uttar Pradesh, Jharkhand, and Assam.
2. Fluoride: Excess fluoride in groundwater is prevalent in many states, leading to fluorosis (dental and skeletal) in affected populations.
3. Uranium: Elevated levels of naturally occurring uranium in groundwater have been detected in multiple states, including Punjab, Haryana, Rajasthan, and Uttar Pradesh, posing radiological and chemical risks.

Sorbitol (2) is a sugar alcohol generally not considered a primary widespread pollutant in this context. Formaldehyde (4) is a chemical that can contaminate water, but it’s less commonly cited as a widespread contaminant across *parts of India* due to natural or broad anthropogenic causes compared to arsenic, fluoride, and uranium, which are often geogenic (naturally occurring in rocks and soil).

40. Which one of the following statements correctly defines PM1 particles

Which one of the following statements correctly defines PM1 particles in air ?

These are suspended particles of diameter more than 10 micron

These are the particles that are filtered by the nose during respiration

These are extreme fine particles of diameter less than 1 micron

These are coarse particles that penetrate directly through the lungs into the bloodstream

This question was previously asked in

UPSC CAPF – 2024

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PM stands for Particulate Matter, which is a mixture of solid particles and liquid droplets found in the air. The number designation (e.g., PM10, PM2.5, PM1) refers to the maximum diameter of the particles in micrometers (microns). PM1 particles are defined as extremely fine particles that have a diameter less than 1 micrometer. These are smaller than PM2.5 and PM10 particles.

PM classification is based on the aerodynamic diameter of airborne particulate matter. PM1 < 1 µm, PM2.5 < 2.5 µm, PM10 < 10 µm. Smaller particles can penetrate deeper into the respiratory system.

PM1 particles are considered among the most harmful air pollutants because their small size allows them to be inhaled deeply into the lungs and potentially enter the bloodstream. They are often associated with combustion processes (vehicle exhaust, industrial emissions, power plants) and can contribute to respiratory and cardiovascular diseases.