Environmental Pollution

Cement manufacturing contributes significantly to global carbon emissions, mainly due to the chemical process involved in producing clinker.

Statement I: Cement industry emissions are estimated to be around 5-8% of global CO₂ emissions, making it a major source of greenhouse gases. Statement II: Silica-bearing clay is indeed mixed with limestone during cement making to provide essential minerals like silicon, aluminum, and iron needed for the final product. Statement III: During clinker production, limestone (calcium carbonate) is heated and converted into lime (calcium oxide), releasing CO₂ in the process. This calcination is the main source of carbon emissions in cement manufacturing.

Both Statements II and III are correct, but only Statement III directly explains the source of carbon emissions mentioned in Statement I.

A circular economy focuses on minimizing waste, reusing resources, and improving efficiency, all of which help lower greenhouse gas emissions and conserve raw materials.

Statement I: Correct By reducing waste and energy use, the circular economy helps cut greenhouse gas emissions.

Statement II: Correct It reduces the need for raw materials through reuse, recycling, and product life extension.

Statement III: Correct It also lowers production waste using efficient and sustainable design and processes.

Many everyday items contain hidden plastics, even if they don't look like typical plastic products.

* I. Cigarette butts – Filters are made of cellulose acetate, a form of plastic. * II. Eyeglass lenses – Usually made from polycarbonate or CR-39 plastic, not glass. * III. Car tyres – Contain synthetic rubber, which includes plastic-based polymers.

All three items contain plastic.

Activated carbon is widely used to clean pollutants because of its unique properties and sustainable production methods.

Statement I: Correct. Activated carbon effectively removes pollutants from industrial effluents due to its high adsorption capacity. It's commonly used in water treatment and pollution control. Statement II: Correct. This is because activated carbon has an extremely large surface area, created by its porous structure, allowing it to trap heavy metals and other contaminants efficiently. Statement III: Correct. Moreover, activated carbon can be produced easily and cost-effectively from carbon-rich wastes like coconut shells, rice husks, and other agricultural residues, making it an eco-friendly option.

Thus, both Statement II and Statement III are correct, and together they explain why Statement I is true.

A. silver iodide and potassium iodide: True Both are used in cloud seeding because their crystalline structures help form ice nuclei, inducing rainfall.

B. silver nitrate and potassium iodide: False Silver nitrate is not used for artificial rainmaking.

C. silver iodide and potassium nitrate: False Potassium nitrate is not used in cloud seeding.

D. silver nitrate and potassium chloride: False Neither chemical is used in artificial rainmaking.

Therefore, option A is correct.

Statement-I: Correct.

Chewing gums are a source of environmental pollution due to several factors:

* Non-biodegradable gum base: Traditional chewing gums often contain polymers like polyisobutylene, polyvinyl acetate, or polyethylene, which do not decompose easily in the environment.

* Littering: Discarded chewing gum remains on sidewalks, streets, and other public spaces, creating an eyesore and requiring significant resources for removal.

Statement-II: Correct and explains Statement-I

* The plastic-like polymers used as gum bases in many chewing gums are the primary reason they are difficult to biodegrade. These polymers contribute significantly to the environmental persistence of chewing gum litter.

Therefore, the correct option is (A): Both Statement-I and Statement-II are correct and Statement-II explains Statement-I.

* Statement 1 is Correct. PFAS are used in a wide range of consumer products, and due to their persistence, they can leach into the environment and contaminate water sources, food, and packaging materials.

* Statement 2 is Correct. PFAS are known as 'forever chemicals' because the strong carbon-fluorine bond makes them highly resistant to natural degradation processes. This persistence leads to their accumulation in the environment.

* Statement 3 is Correct. Because PFAS don't break down easily, they can build up in the tissues of animals and humans over time, leading to potential health concerns.


_Therefore, all three statements are correct._

Power plants burning fossil fuels (coal, oil, and, to a lesser extent, natural gas) are the largest source of sulfur dioxide emissions globally. Coal, in particular, contains high levels of sulfur, and when burned, it releases large amounts of SO₂.

* Locomotives, especially older ones, use diesel fuel which contains sulfur. While locomotives do contribute to sulfur dioxide (SO₂) emissions, their contribution is relatively minor compared to larger industrial sources.

* Ships, particularly large cargo vessels and tankers, often use bunker fuel, a heavy, sulfur-rich fuel oil. This contributes significantly to SO₂ emissions, particularly in maritime regions. However, they are still overshadowed by emissions from power plants

* The process of extraction of metals from ore involves heating ores that contain sulfur compounds, releasing SO₂ into the atmosphere. However, its contribution is less than that of power plants.

* Membrane Bioreactors are often discussed in the context of: D. Wastewater treatment technologies.

* Membrane Bioreactors (MBRs) combine a membrane process like microfiltration or ultrafiltration with a biological wastewater treatment process. * They are used to improve the quality of treated wastewater and are known for their efficiency in removing contaminants.

* Statement 1 is Correct: Gold mining is poisoning Amazon forests with mercury. To separate the gold, miners mix liquid mercury into the sediment, which forms a coating around the gold.

* Statement 2 is Correct: Fly ash generated by TPPs is one of the ways mercury is released into the environment. Fly ash is usually disposed of in ash ponds in the form of ash slurry, forming an aquatic ecosystem of its own. Coal-based TPPs are the major source of mercury – the ninth most toxic element found on earth — emissions into the environment. Mercury contributed over 80 percent of emissions released by the TPPs, according to 2016 estimates by the Delhi-based think-tank Centre for Science and Environment.

* Statement 3 is Incorrect: While mercury is unquestionably toxic, toxicology works on the principle of dose: "The dose makes the poison." Hence, scientific bodies define reference doses (RfD) or tolerable intake levels, not zero exposure. WHO's Provisional Tolerable Weekly Intake (PTWI) for methylmercury (from fish) → 1.6 µg/kg body weight/week and 1 µg/litre for total mercury in drinking water. If no safe level truly existed: Mercury would be completely banned, not regulated.

NOTE: UPSC usually considers extreme statement to be wrong.

* Statement 1 is correct: Role of Biofilters in Recirculating Aquaculture System (RAS): Biofilters provide waste treatment by removing uneaten fish feed. Biofilters in a RAS help in waste treatment by removing uneaten fish feed and other organic matter from the water. The biofilter media provide a surface for beneficial bacteria to grow, which help in breaking down and removing these wastes.

* Statement 2 is correct: Biofilters convert ammonia present in fish waste to nitrate. One of the primary functions of biofilters in a RAS is to convert toxic ammonia (produced from fish waste) into less harmful nitrate. Beneficial bacteria in the biofilter media perform nitrification, a process where ammonia is first converted to nitrite and then further converted to nitrate.

* Statement 3 is incorrect: Biofilters do not increase phosphorus as a nutrient for fish in the water. Their primary role is to remove wastes and convert ammonia to nitrate. Phosphorus levels in the water are managed through other means, such as fish feed formulation and water quality management.

Therefore, option (B) is the correct answer.

Statement 1 is correct. PET fibres can be blended with cotton or wool to improve properties like wrinkle resistance and durability.

Statement 2 is incorrect. Not all PET containers are suitable for all alcoholic beverages. Some PET can leach chemicals at high temperatures or with certain types of alcohol. It's important to check for specific suitability indicators on the packaging.

Statement 3 is correct. PET bottles are one of the most commonly recycled plastics. They can be reprocessed into various products like clothing fibres, new bottles, or building materials.

Statement 4 is incorrect. Incineration of PET, like most plastics, generates greenhouse gas emissions, including carbon dioxide. While PET has a lower emission profile compared to some other plastics, it's still not a zero-emission disposal method.

Remember: Statements like store any kind of alcoholic beverages are vague & ambiguous, so they ought to be eliminated. Also, incineration of any substance cannot be environment friendly as it would definitely release GHGs. Hence the only Option left is Option A. Therefore, the correct statements are 1 and 3.

Acid rain is primarily caused by the excess presence of nitrogen oxide and sulphur dioxide in the environment.

* Carbon monoxide is not a direct cause of acid rain. It is a pollutant that contributes to the formation of ground-level ozone, but it does not lead to the production of acid rain.

* Nitrogen oxides, which include nitric oxide and nitrogen dioxide, are major contributors to acid rain. When these gases react with water, oxygen, and other substances in the atmosphere, they form nitric acid, a key component of acid rain.

* Ozone is not a direct cause of acid rain. While ozone can have negative environmental impacts, it is not a precursor to the formation of acid rain.

* Sulphur dioxide is another primary contributor to acid rain. When Sulphur dioxide combines with water, oxygen, and other substances in the atmosphere, it forms sulphuric acid, which is also a major component of acid rain.


Statement 1 is correct. The WHO recommends that the 24-hour mean of PM2.5 should not exceed 15 ug/m³ and the annual mean should not exceed 5 ug/m³. These are the current most stringent guidelines set by WHO to protect public health.

Statement 2 is incorrect. Ozone pollution typically peaks during sunny and stagnant weather conditions, not during inclement weather like rain or storms.

Statement 3 is incorrect. While PM10 (≤ PM10) particles can enter the deep lungs and cause respiratory issues, it's the much finer PM2.5 (≤ PM2.5) particles and ultrafine particles that effectively penetrate the lung barrier (alveoli) to enter the bloodstream, affecting the heart, brain, and other organs. PM10 typically deposits in larger airways, whereas PM2.5's tiny size allows it to cross into the circulatory system, making it more dangerous.

Statement 4 is correct. Excessive ozone exposure can trigger asthma attacks and worsen respiratory problems. Ozone irritates the respiratory tract, making it harder to breathe.

Statement 1 is Incorrect: Copper smelting plants are not typically associated with the release of lethal quantities of carbon monoxide into the environment; the primary gaseous pollutant of concern is sulfur dioxide. Statement 2 is Correct: Copper slag is a byproduct of the smelting process that contains heavy metals such as arsenic, lead, and cadmium. These metals can leach into the environment, potentially contaminating soil and groundwater resources. Statement 3 is Correct: Copper smelting plants are a major source of sulfur dioxide (SO2) emissions. This occurs because most copper ores are sulfide minerals (like chalcopyrite), and the sulfur within the ore is oxidized and released as SO2 gas during the roasting and smelting processes.

Statement 1 is Correct: The friction and mechanical wear between brake pads and discs in motor vehicles generate iron-rich particulate matter, which can oxidize to form magnetite nanoparticles.

Statement 2 is Correct: High-temperature combustion within vehicle engines produces magnetite as a byproduct of fuel burning and engine component wear, which is then released as an environmental pollutant.

Statement 3 is Incorrect: Microwave stoves use electromagnetic radiation to heat food; they do not involve combustion or mechanical abrasion that would release magnetite particles into the environment.

Statement 4 is Correct: Power plants, especially coal-fired ones, are significant sources of magnetite. The high-temperature combustion of fossil fuels produces fly ash that contains magnetic iron oxides.

Statement 5 is Incorrect: Telephone lines carry electrical or optical signals and generate electromagnetic fields, but they do not undergo processes that emit physical magnetite particles.

* The R2 Code of Practices is a tool available for promoting the adoption of environmentally responsible practices in the electronics recycling industry.

* R2 stands for Responsible Recycling. The Code of Practices outlines a set of standards that electronics recyclers should follow to ensure responsible handling of electronic waste.

Statement 1 is correct. Furnace oil is indeed a product of oil refineries. It is a dark viscous residual fuel obtained by blending heavier components of crude oil.

Statement 2 is correct. Furnace oil is widely used in industries like cement, steel, and textiles for power generation and heating. It is burned in boilers, furnaces, and engines to produce energy.

Statement 3 is correct. Furnace oil contains high sulfur content, and its combustion releases sulfur oxides (SOₓ), contributing to air pollution and acid rain.

Triclosan (sometimes abbreviated as TCS) is an antibacterial and antifungal agent present in some consumer products, including - toothpaste, - soaps, - detergents, - toys, - surgical cleaning treatments.

* Bisphenol A (BPA) is a key component in the manufacture of polycarbonate plastics.

* Polycarbonate plastics are a type of synthetic plastic material that is known to contain Bisphenol A (BPA) as a structural component.

* BPA is used in the production of polycarbonate plastics, which are commonly used in various consumer products such as Water bottles, Food storage containers, Household electronics, Eyeglass lenses, Compact discs (CDs) and digital versatile discs (DVDs)

* BPA has raised health concerns due to its potential to act as an endocrine disruptor, which can interfere with the body's hormonal system.

1. Copper slag is a by-product generated during the extraction and refining of copper. It can be used as a partial replacement for sand in concrete production, thus reducing the demand for natural resources. This reduces the environmental impact associated with sand mining.

2. Cold mix asphalt technology involves producing asphalt mixtures at lower temperatures compared to traditional hot mix asphalt. This results in reduced energy consumption during production and lower emissions of greenhouse gases. Cold mix asphalt also allows for the use of recycled materials, further enhancing its environmental sustainability.

3. Geotextiles are synthetic materials used in road construction for various purposes such as soil stabilisation, drainage, and erosion control. They can help in reducing the need for excessive excavation and use of natural resources like stone and gravel, thereby minimizing environmental impact.

4. Hot mix asphalt technology involves producing asphalt mixtures at high temperatures. While it provides excellent performance properties for roads, it typically requires higher energy consumption during production compared to cold mix asphalt technology.

5. Portland cement is a key ingredient in concrete production. While it is widely used in construction, its production process is energy-intensive and emits significant amounts of carbon dioxide, contributing to greenhouse gas emissions.

Therefore, the correct answer is A. 1, 2, and 3 only.

Statement 1 is correct: Coal ash, a by-product of coal combustion in power plants, contains various heavy metals including arsenic, lead, and mercury. These metals can pose environmental and health hazards. These toxic elements can leach into water bodies and contaminate soil.

Statement 2 is correct: The combustion of coal in power plants releases releases sulfur dioxide (SO₂), which contributes to acid rain and respiratory issues. It also emits oxides of nitrogen (NOₓ), which play a major role in smog formation and air pollution.

Statement 3 is correct: Indian coal, particularly the variety found in the eastern and central regions, is known for its high ash content (30-50%), which reduces its calorific value and increases pollution levels.Due to its high ash content, Indian thermal power plants generate large quantities of fly ash.

Therefore, all three statements are correct.

Benzene is a colorless or light yellow liquid at room temperature and is a well-known environmental pollutant. It is widely present in the environment due to various natural and human-made sources..

1. Automobiles, especially those running on petrol, are a significant source of benzene pollution. Since benzene is a component of petroleum products, including motor fuels, its combustion in vehicle engines releases benzene into the air, contributing significantly to air pollution.

2. Tobacco smoke is a source of benzene exposure. Both active smoking and passive smoking introduce benzene into the body, as tobacco smoke contains benzene. Prolonged exposure to such smoke increases health risks.

3. Wood burning releases benzene and other pollutants like polycyclic aromatic hydrocarbons (PAHs) due to incomplete combustion. Hence, wood burning is a source of benzene pollution.

4. Varnished wooden furniture can be a source of benzene exposure but it is less direct and typically with lower exposure levels once the varnish has cured. Therefore, it is not considered a significant source of benzene pollution.

5. Polyurethane-based products do not contribute significantly to benzene pollution. They are more associated with volatile organic compounds (VOCs) and other chemicals rather than benzene itself.

Thus, the major contributors to benzene pollution are automobile emissions, tobacco smoke, and wood burning . Hence the correct answer is A. 1, 2 and 3 only.

Because of their small size, marine animals like fish, shellfish, and plankton can easily ingest microbeads. These plastic particles can block their digestive systems, leading to starvation or death.

Additionally, microbeads might absorb pollutants and toxins present in the water, concentrating them in the food chain and potentially harming larger predators, including humans.

All three statements (1, 2, and 3) are correct.

Statement 1 is correct: Agricultural soils are a major source of nitrogen oxides (NOx) emissions, primarily nitrous oxide (NO). This occurs during microbial processes in the soil, such as nitrification and denitrification.

Statement 2 is correct: Cattle release significant amounts of ammonia (NH) into the atmosphere through their urine and manure. This ammonia contributes to air pollution and can have negative environmental consequences.

Statement 3 is correct: The poultry industry releases various reactive nitrogen compounds into the environment, including ammonia, nitrous oxide, and nitrogen oxides. These emissions come from poultry manure and the use of nitrogen-based fertilizers in feed production.

Extended Producer Responsibility (EPR) in E-waste Management Rules, 2011 Makes producers of electrical and electronic equipment (EEE) responsible for the collection and channelization of e-waste after its end-of-life. This promotes responsible production and encourages proper e-waste disposal.

EPR in Plastic Waste Management Rules, 2016 Extends the EPR principle to plastic waste. Producers, importers, and brand owners are accountable for managing plastic packaging waste after consumption.

* Aral Sea: The Aral Sea was once one of the world's largest inland lakes, but due to extensive water diversion for irrigation projects, particularly from the Amu Darya and Syr Darya rivers, it has shrunk by over 75% since the 1960s. This has led to severe environmental, economic, and social consequences, including increased salinity, loss of marine life, and desertification.


* Black Sea: While the Black Sea faces environmental challenges such as pollution, biodiversity loss, and reduced oxygen levels in deep waters, it has not experienced significant drying like the Aral Sea.

* Lake Baikal: Lake Baikal in Russia is the deepest and oldest freshwater lake in the world, containing about 20% of the world's unfrozen freshwater supply. Although it experiences natural fluctuations in water levels, it has not undergone severe drying like the Aral Sea.

Thus, the correct answer is option (d).

Bioremediation is a technique that utilizes living organisms, primarily microorganisms like bacteria and fungi, to remove or neutralize contaminants from polluted environments. It essentially harnesses and accelerates natural biodegradation processes for environmental cleanup.

Statement 1 (correct): This accurately describes a key advantage of bioremediation. It leverages and accelerates natural biodegradation processes by introducing suitable microorganisms or optimizing environmental conditions.

Statement 2 (incorrect): Bioremediation can be effective for many contaminants but not all. Heavy metals like cadmium and lead are often not readily broken down or removed completely. They might be transformed or immobilized, but not necessarily eliminated.

Statement 3 (correct): Genetic engineering offers a promising approach for developing microorganisms with enhanced capabilities for bioremediation. These engineered microbes can target specific pollutants or work more efficiently in challenging environments.


The Climate and Clean Air Coalition (CCAC) to Reduce Short-Lived Climate Pollutants was launched by a joint effort of 1. United Nations Environment Programme (UNEP) 2. Six countries Bangladesh, Canada, Ghana, Mexico, Sweden, and the United States

Statement 1 is incorrect. The Climate and Clean Air Coalition (CCAC) is not a unique initiative of the G20 group of countries. While some G20 members were involved in its launch, the CCAC has grown into a broader coalition that includes over 160 governments, intergovernmental organisations, and non-governmental organisations.

Statement 2 is correct. The CCAC's primary focus is indeed on reducing emissions of potent short-lived climate pollutants (SLCPs). These include Methane (CH4), Black Carbon (BC) and Hydrofluorocarbons (HFCs).

Statement 1 is Incorrect: Carbon dioxide (CO2) is a greenhouse gas primarily responsible for global warming, but it is not one of the eight pollutants considered in the calculation of India's National Air Quality Index (AQI).

Statement 2 is Correct: Carbon monoxide (CO) is one of the eight pollutants monitored under the National AQI, as it is a toxic gas produced by incomplete combustion that affects oxygen transport in the blood.

Statement 3 is Correct: Nitrogen dioxide (NO2) is included in the AQI calculation; it is a major air pollutant emitted from vehicle exhausts and industrial processes that causes respiratory issues.

Statement 4 is Correct: Sulphur dioxide (SO2) is a criteria pollutant for the AQI, primarily released from the burning of fossil fuels in power plants and industrial facilities.

Statement 5 is Incorrect: Methane (CH4) is a potent greenhouse gas and a precursor to ground-level ozone, but it is not directly measured or included as a parameter in the National AQI calculation.

Note: The National Air Quality Index (AQI) in India considers eight pollutants: Particulate Matter (PM10), Particulate Matter (PM2.5), Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2), Carbon Monoxide (CO), Ozone (O3), Ammonia (NH3), and Lead (Pb).