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101. Which major source of water pollution is the largest contributor to the pathogen load and the high Biochemical Oxygen Demand (${BOD}$) in rivers and lakes?
ⓐ. Untreated domestic sewage
ⓑ. Thermal power plant cooling water
ⓒ. Runoff from fertilized fields
ⓓ. Leakage from petroleum pipelines
Correct Answer: Untreated domestic sewage
Explanation: Domestic sewage contains large amounts of biodegradable organic matter (increasing ${BOD}$) and disease-causing microorganisms like bacteria and viruses (pathogens). Its untreated discharge into water bodies is the primary cause of both high ${BOD}$ and waterborne diseases.
102. The discharge of wastewater containing extremely toxic and non-biodegradable heavy metals like Lead (${Pb}$), Chromium (${Cr}$), and Mercury (${Hg}$) into aquatic systems is characteristic of pollution from:
ⓐ. Urban stormwater runoff
ⓑ. Industrial effluents (e.g., metal finishing, tanneries, chemical plants)
ⓒ. Animal husbandry and dairy farms
ⓓ. Municipal solid waste leachate
Correct Answer: Industrial effluents (e.g., metal finishing, tanneries, chemical plants)
Explanation: Heavy metals are widely used in specialized industrial processes such as electroplating, metal finishing, tanning (leather processing), and chemical manufacturing. Unlike organic waste, these metals are not biodegradable and persist, accumulating in aquatic organisms and posing severe health risks.
103. Eutrophication is the rapid aging of a lake due to an excessive increase in primary production. This process is triggered mainly by the input of Nitrates (${NO}_3^-$) and Phosphates (${PO}_4^{3-}$) originating from which cause?
ⓐ. Discharge of waste hot water
ⓑ. Release of detergents from households
ⓒ. Agricultural runoff (chemical fertilizers)
ⓓ. Leaching of radioactive waste
Correct Answer: Agricultural runoff (chemical fertilizers)
Explanation: While detergents contribute phosphates (Option B), the massive scale of the problem is due to agricultural runoff. Excess chemical fertilizers, rich in ${NO}_3^-$ and ${PO}_4^{3-}$, are washed from fields into surface water, fueling the rapid and uncontrolled growth of algae (algal blooms) that characterize eutrophication.
104. The presence of which type of microorganism is commonly used as a primary indicator to detect contamination from human fecal matter (domestic sewage) in a water sample?
ⓐ. *Clostridium botulinum*
ⓑ. Cyanobacteria
ⓒ. *Vibrio cholerae*
ⓓ. Coliform bacteria (e.g., *E. coli*)
Correct Answer: Coliform bacteria (e.g., *E. coli*)
Explanation: Coliform bacteria, particularly *Escherichia coli* (*E. coli*), are naturally present in the intestinal tracts and feces of humans and warm-blooded animals. Their presence in water indicates that the water has been contaminated by fecal matter, suggesting a high probability of other, more dangerous pathogens being present.
105. Organochlorine compounds, such as ${DDT}$ and Lindane, are highly non-biodegradable and persist in the environment, exhibiting the phenomenon of biomagnification. Which source is the primary origin of these pollutants in aquatic systems?
ⓐ. Agricultural runoff (pesticides)
ⓑ. Paper and pulp industry effluents
ⓒ. Thermal power plants
ⓓ. Domestic sewage (human waste)
Correct Answer: Agricultural runoff (pesticides)
Explanation: ${DDT}$ and related organochlorine pesticides were historically applied heavily in agriculture to control pests. Despite bans in many countries, they persist in soil and are washed into water bodies through runoff. Their fat-soluble and non-biodegradable nature leads to their accumulation and biomagnification up the food chain.
106. Excessive sediment load in rivers, often characterized by suspended clay, silt, and soil particles, is a major non-point source of pollution originating mainly from:
ⓐ. The paper and pulp industry
ⓑ. Agricultural practices (soil erosion) and construction sites
ⓒ. Leakage from underground storage tanks
ⓓ. Municipal sewage discharge
Correct Answer: Agricultural practices (soil erosion) and construction sites
Explanation: Poor farming techniques, such as plowing hillsides or over-tilling, leave soil exposed and vulnerable to erosion by rain. Similarly, clear-cut construction sites result in a massive amount of soil washing into nearby water bodies, increasing turbidity, destroying aquatic habitats, and interfering with photosynthesis.
107. When untreated domestic sewage is discharged into a river, the initial effect on the river’s Dissolved Oxygen (${DO}$) concentration is:
ⓐ. ${DO}$ increases due to the release of oxygen from sewage.
ⓑ. ${DO}$ remains unchanged, regardless of the organic load.
ⓒ. ${DO}$ decreases slightly, but recovers quickly downstream.
ⓓ. ${DO}$ drops sharply due to the rapid activity of aerobic decomposers.
Correct Answer: ${DO}$ drops sharply due to the rapid activity of aerobic decomposers.
Explanation: Sewage contains vast amounts of organic matter. Aerobic bacteria immediately begin decomposing this matter, a process that consumes large amounts of dissolved oxygen. This rapid consumption causes the Dissolved Oxygen (${DO}$) concentration to drop sharply downstream of the sewage outfall, potentially creating an anaerobic zone that is lethal to fish and other aquatic life.
108. Which debilitating human disease is associated with the consumption of water or food contaminated by Cadmium (${Cd}$), a heavy metal released primarily in industrial effluents?
ⓐ. Minamata disease
ⓑ. Blue baby syndrome (Methemoglobinemia)
ⓒ. Itai-Itai disease
ⓓ. Black foot disease
Correct Answer: Itai-Itai disease
Explanation: Itai-Itai disease (meaning “it hurts, it hurts” in Japanese) is a severe form of chronic Cadmium poisoning. The Cadmium typically originates from industrial mining and smelting waste and leads to fragile bones, severe pain, and kidney failure. Minamata disease is caused by Mercury.
109. The primary effect of introducing large quantities of biodegradable organic matter (from sewage) into a water body is measured by its:
ⓐ. Biochemical Oxygen Demand (${BOD}$)
ⓑ. Chemical Oxygen Demand (${COD}$)
ⓒ. Dissolved Oxygen (${DO}$) saturation
ⓓ. ${Total Suspended Solids}$ (${TSS}$)
Correct Answer: Biochemical Oxygen Demand (${BOD}$)
Explanation: BOD is a direct measure of the amount of dissolved oxygen consumed by aerobic microorganisms when decomposing organic matter in a water sample over a set period (usually 5 days at $20^\circ{C}$). It is the most common parameter for assessing the pollution strength caused by sewage and other decomposable organic waste.
110. Which major class of water pollutants is derived from the leaching of solid waste in landfills and open dumps, often containing a complex mixture of organic and inorganic compounds?
ⓐ. Agricultural runoff
ⓑ. Industrial cooling water
ⓒ. Landfill leachate
ⓓ. Thermal discharge
Correct Answer: Landfill leachate
Explanation: As water percolates through municipal solid waste (trash) in landfills, it dissolves and carries away a highly contaminated liquid known as leachate. This leachate is a complex pollutant mixture containing high concentrations of biodegradable organic compounds, heavy metals, and persistent organic chemicals, making it a severe threat to both groundwater and surface water.
111. Which term describes the final, severe consequence of eutrophication, where the decomposition of massive algal blooms leads to the death of fish and other aerobic aquatic life?
ⓐ. Hypoxia (oxygen depletion)
ⓑ. Thermal pollution
ⓒ. Reduced turbidity
ⓓ. Acidification
Correct Answer: Hypoxia (oxygen depletion)
Explanation: The dense algal bloom, fueled by excess nutrients, eventually dies. The subsequent aerobic decomposition of this large biomass by bacteria consumes vast amounts of the water’s Dissolved Oxygen (${DO}$). This leads to an anoxic (zero oxygen) or hypoxic (low oxygen) state, causing fish and other aerobic organisms to suffocate and die.
112. The process of Biomagnification is characterized by the pollutant concentration increasing sequentially in which part of the ecosystem structure?
ⓐ. From a source to a sink (reservoir)
ⓑ. Upward through successive trophic levels in a food chain
ⓒ. From water into the surrounding soil/sediment
ⓓ. Within a single organism over its lifetime (bioaccumulation)
Correct Answer: Upward through successive trophic levels in a food chain
Explanation: Biomagnification occurs because non-biodegradable, fat-soluble pollutants (like ${DDT}$ or Methylmercury) are concentrated at each step of the food chain. Organisms at higher trophic levels consume many contaminated organisms from the lower levels, causing the pollutant’s concentration in their tissues to be orders of magnitude higher than in the environment or lower-level organisms.
113. Which water-borne disease, caused by the bacterium Vibrio cholerae, is strongly linked to the consumption of water or food contaminated by raw sewage?
ⓐ. Typhoid fever
ⓑ. Amoebiasis
ⓒ. Cholera
ⓓ. Hepatitis A
Correct Answer: Cholera
Explanation: Cholera is the acute diarrheal illness specifically caused by the toxin produced by the bacterium Vibrio cholerae. It is a classic example of a water-borne disease that spreads rapidly in areas with poor sanitation and untreated sewage, as the bacterium is passed through the fecal-oral route.
114. The dense surface growth of algae, known as an algal bloom, affects water quality negatively by doing all of the following EXCEPT:
ⓐ. Releasing toxins that can harm fish and humans.
ⓑ. Blocking sunlight to submerged aquatic vegetation.
ⓒ. Reducing the water’s aesthetic quality.
ⓓ. Causing an immediate increase in the concentration of Dissolved Oxygen (${DO}$).
Correct Answer: Causing an immediate increase in the concentration of Dissolved Oxygen (${DO}$).
Explanation: While algae produce ${O}_2$ during the day through photosynthesis, the overall and most detrimental effect of a bloom is the massive consumption of ${DO}$ when the algae die and decompose. Therefore, the effect is a net decline and subsequent hypoxia, not an increase.
115. Which of these pollutants, historically used as a pesticide, is the classic example of a compound that undergoes significant biomagnification in both aquatic and terrestrial food chains, leading to detrimental effects on top predators like raptors?
ⓐ. DDT (Dichlorodiphenyltrichloroethane)
ⓑ. Nitrate ions (${NO}_3^-$)
ⓒ. Carbon Monoxide (${CO}$)
ⓓ. Sulphur Dioxide (${SO}_2$)
Correct Answer: DDT (Dichlorodiphenyltrichloroethane)
Explanation: DDT is a highly persistent, non-biodegradable, and fat-soluble organochlorine compound. Its high lipophilicity (fat-solubility) causes it to accumulate in the fatty tissues of organisms and dramatically biomagnify up the food chain, leading to reproductive failure (e.g., eggshell thinning) in apex predators.
116. The excessive nutrient load that drives eutrophication primarily stimulates the massive growth of:
ⓐ. Fish and large aquatic invertebrates
ⓑ. Algae and Cyanobacteria (Phytoplankton)
ⓒ. Aerobic decomposers
ⓓ. Macrophytes (large, rooted aquatic plants)
Correct Answer: Algae and Cyanobacteria (Phytoplankton)
Explanation: Eutrophication is fueled by excess nutrients (${N}$ and ${P}$), which act as fertilizer for the microscopic primary producers: algae and cyanobacteria (blue-green algae). Their uncontrolled growth forms the dense algal blooms that characterize the first stage of eutrophication.
117. In a food chain consisting of algae, zooplankton, small fish, and large fish, where would the highest concentration of a fat-soluble, non-biodegradable pollutant like ${DDT}$ be found due to biomagnification?
ⓐ. Algae (Primary Producer)
ⓑ. Zooplankton (Primary Consumer)
ⓒ. Large fish (Top Consumer)
ⓓ. Water itself (The medium)
Correct Answer: Large fish (Top Consumer)
Explanation: According to the principle of biomagnification, the concentration of the pollutant increases at each successive trophic level. Therefore, the large fish, being the top consumer in this chain, will have the highest concentration of the persistent pollutant.
118. Methemoglobinemia (Blue Baby Syndrome), where the blood’s oxygen-carrying capacity is reduced, is a consequence of ingesting contaminated drinking water primarily high in which agricultural pollutant?
ⓐ. Cadmium
ⓑ. Mercury
ⓒ. Pesticides
ⓓ. Nitrate ions (${NO}_3^-$)
Correct Answer: Nitrate ions (${NO}_3^-$)
Explanation: High concentrations of Nitrate ions (${NO}_3^-$) in drinking water, especially for infants, can lead to their reduction to nitrite (${NO}_2^-$) in the body. Nitrite then oxidizes the iron in haemoglobin, forming methemoglobin, which cannot carry oxygen, leading to the characteristic bluish skin color.
119. The primary effect of introducing large quantities of biodegradable organic matter (from sewage) into a water body is measured by its:
ⓐ. Biochemical Oxygen Demand (${BOD}$)
ⓑ. Chemical Oxygen Demand (${COD}$)
ⓒ. Dissolved Oxygen (${DO}$) saturation
ⓓ. ${Total Suspended Solids}$ (${TSS}$)
Correct Answer: Biochemical Oxygen Demand (${BOD}$)
Explanation: The Biochemical Oxygen Demand (${BOD}$) is the gold standard measurement for the impact of organic pollution (like sewage). It quantifies the amount of dissolved oxygen required by aerobic microorganisms to break down the organic material in a water sample, thereby directly indicating the pollution load.
120. The severe neurological disorder known as Minamata disease is a devastating example of toxic water pollution caused by the biomagnification of:
ⓐ. Cadmium, affecting bones and kidneys.
ⓑ. Lead, causing general developmental and nervous system damage.
ⓒ. Methylmercury, affecting the central nervous system.
ⓓ. Arsenic, causing skin lesions and Blackfoot disease.
Correct Answer: Methylmercury, affecting the central nervous system.
Explanation: Minamata disease is the clinical syndrome of severe poisoning caused by the consumption of fish and shellfish contaminated with Methylmercury (${CH}_3{Hg}^+$). Methylmercury is a highly neurotoxic compound that bioaccumulates and biomagnifies efficiently through the aquatic food chain.
121. The excessive, long-term application of nitrogenous fertilizers in agriculture can negatively affect soil by:
ⓐ. Significantly increasing the soil’s ${pH}$ (making it more alkaline).
ⓑ. Increasing soil acidity and potentially releasing toxic aluminum ions.
ⓒ. Promoting the growth of beneficial nitrogen-fixing bacteria.
ⓓ. Decreasing the rate of surface water runoff and erosion.
Correct Answer: Increasing soil acidity and potentially releasing toxic aluminum ions.
Explanation: Nitrogen fertilizers, particularly ammonium-based ones (${NH}_4^+$), undergo nitrification in the soil, which releases ${H}^{+}$ ions. This process consumes the soil’s alkalinity (buffering capacity) and leads to acidification. Low ${pH}$ mobilizes ${Al}^{3+}$ ions, which are toxic to plant roots and soil organisms.
122. Which class of pesticides is known for its high persistence in the soil, leading to long-term contamination issues and biomagnification risk?
ⓐ. Organophosphates (e.g., Malathion)
ⓑ. Carbamates (e.g., Carbaryl)
ⓒ. Pyrethroids (e.g., Permethrin)
ⓓ. Organochlorines (e.g., DDT, Aldrin)
Correct Answer: Organochlorines (e.g., DDT, Aldrin)
Explanation: Organochlorine pesticides are highly stable due to their chemical structure. They are resistant to microbial degradation, hydrolysis, and photolysis, giving them extremely long half-lives (decades) in the soil. This persistence is the primary reason for their ban in many countries, as they pose persistent soil and food chain contamination risks.
123. The key challenge presented by plastic waste (e.g., polythene bags) as a soil pollutant is that it:
ⓐ. Leaches toxic heavy metals into the soil quickly.
ⓑ. Reacts with fertilizer residues to form explosive compounds.
ⓒ. Is non-biodegradable and physically impedes water infiltration and aeration.
ⓓ. Significantly increases the overall nutrient content of the soil.
Correct Answer: Is non-biodegradable and physically impedes water infiltration and aeration.
Explanation: Most plastics are non-biodegradable and break down very slowly into microplastics, persisting in the soil indefinitely. Larger pieces physically impede the movement of air and water through the soil profile, disrupting root growth, microbial activity, and natural drainage, leading to waterlogging or anaerobic conditions.
124. The main source of radioactive waste pollution in soil that comes from non-military or non-power plant origins is typically:
ⓐ. Land application of phosphate fertilizers containing trace uranium and thorium.
ⓑ. The natural decay of atmospheric carbon-14.
ⓒ. Disposal of spent fuel rods from research reactors.
ⓓ. Runoff from nuclear medicine facilities.
Correct Answer: Land application of phosphate fertilizers containing trace uranium and thorium.
Explanation: Phosphate rock, used to manufacture phosphate fertilizers, naturally contains trace amounts of long-lived radioisotopes like Uranium-238 (${U-238}$) and Thorium-232 (${Th-232}$) and their decay products. Although the concentrations are low, the consistent and widespread application of these fertilizers leads to the accumulation of these radioactive elements in agricultural soil over decades, which is a key non-conventional source of soil contamination.
125. The extensive use of insecticides and fungicides can have a profound negative impact on soil fertility primarily by:
ⓐ. Increasing the concentration of toxic ${Al}^{3+}$ ions in the soil.
ⓑ. Raising the ${BOD}$ of the soil moisture significantly.
ⓒ. Causing excessive soil erosion and sediment runoff.
ⓓ. Killing beneficial non-target microorganisms like nitrogen-fixing and nitrifying bacteria.
Correct Answer: Killing beneficial non-target microorganisms like nitrogen-fixing and nitrifying bacteria.
Explanation: Pesticides are designed to be toxic and often lack specificity. When applied to the soil, they can indiscriminately kill or suppress the activity of crucial non-target soil microbiota, including bacteria and fungi responsible for decomposing organic matter, cycling nutrients (like nitrogen fixation and nitrification), and maintaining soil structure, thus severely reducing soil fertility.
126. Herbicides (weed killers) are a major source of soil pollution. The primary mode of degradation for most modern organic herbicides in the soil environment is:
ⓐ. Photolysis (breakdown by sunlight).
ⓑ. Hydrolysis (breakdown by water).
ⓒ. Microbial degradation (breakdown by soil bacteria).
ⓓ. Thermal decomposition (breakdown by heat).
Correct Answer: Microbial degradation (breakdown by soil bacteria).
Explanation: Most modern organic herbicides are designed to be effective in the short term but then degrade rapidly to prevent long-term environmental persistence. The principal mechanism for this rapid breakdown in the soil is microbial degradation, where soil bacteria and fungi metabolize the chemical compounds into simpler, less harmful substances.
127. Which component of soil pollution poses a threat because it leads to the accumulation of excess salts in the root zone, potentially causing plasmolysis and death of crop plants?
ⓐ. Chemical fertilizers
ⓑ. Heavy metals
ⓒ. Organic pesticides
ⓓ. Radioactive isotopes
Correct Answer: Chemical fertilizers
Explanation: Chemical fertilizers are salts (e.g., ${KCl}, {NH}_4{NO}_3$). Over-application or poor irrigation practices, especially in arid regions, can lead to the build-up of these dissolved salts in the topsoil, a condition known as salinization. The high salt concentration increases the osmotic potential of the soil solution, drawing water out of the plant roots (plasmolysis) and preventing water uptake.
128. Microplastics are fragments of plastic less than $5{ mm}$ in size that are increasingly found in soil. Their primary environmental concern, beyond physical impediment, is their ability to:
ⓐ. Quickly mineralize into inert silicon compounds.
ⓑ. Adsorb and concentrate other persistent organic pollutants and heavy metals.
ⓒ. Serve as a readily available food source for earthworms.
ⓓ. Significantly reduce the soil’s moisture holding capacity.
Correct Answer: Adsorb and concentrate other persistent organic pollutants and heavy metals.
Explanation: Due to their large surface area-to-volume ratio and hydrophobic nature, microplastics in the soil act as sinks for other toxic substances. They readily adsorb persistent organic pollutants (like ${PCBs}$) and heavy metals onto their surfaces. This concentrated package of toxins can then be ingested by soil organisms, facilitating the entry of multiple pollutants into the food web.
129. The most significant contamination source associated with the large-scale disposal of municipal and industrial waste (landfills) that ultimately affects soil is:
ⓐ. Airborne ash from waste combustion.
ⓑ. Direct dumping of heavy machinery.
ⓒ. Leachate (a highly contaminated liquid generated as water percolates through the waste).
ⓓ. The spread of pathogenic spores by scavenging birds.
Correct Answer: Leachate (a highly contaminated liquid generated as water percolates through the waste).
Explanation: As rainwater filters through the layers of garbage in a landfill, it dissolves toxic compounds, including acids, heavy metals, and organic contaminants. This resulting highly noxious liquid, leachate, poses the greatest threat to soil (and groundwater) when it escapes the landfill liner, leading to severe and complex chemical contamination.
130. A key pathway by which radioactive contaminants from industrial or medical sources enter and pollute the soil is through:
ⓐ. Direct atmospheric condensation from the stratosphere.
ⓑ. Improper storage and disposal of low-level radioactive waste (LLRW).
ⓒ. High-altitude aircraft engine emissions.
ⓓ. The natural decay of potassium fertilizer.
Correct Answer: Improper storage and disposal of low-level radioactive waste (LLRW).
Explanation: While nuclear accidents are dramatic, much of the long-term radioactive soil contamination comes from the improper handling and disposal of Low-Level Radioactive Waste (LLRW) generated by hospitals, research facilities, and certain industries. If this waste is not secured in specialized disposal sites, leakage and decay can release radionuclides into the soil and water over long periods.
131. The primary mechanism by which persistent soil pollutants like heavy metals (${Cd}, {Pb}$) and organochlorine pesticides negatively impact human health is through:
ⓐ. Direct skin contact with polluted soil during farming.
ⓑ. Inhalation of gases released from the polluted soil.
ⓒ. Entry into the human food chain via crop absorption (food contamination).
ⓓ. Increased fungal growth on stored grain.
Correct Answer: Entry into the human food chain via crop absorption (food contamination).
Explanation: Persistent soil pollutants, particularly heavy metals and lipid-soluble organic compounds, can be absorbed by plant roots and translocated to the edible parts of crops. This pathway, known as crop uptake, introduces the contaminants into the human diet, leading to chronic low-dose exposure and adverse health effects.
132. How does the presence of non-biodegradable plastics (like microplastics) in agricultural soil negatively impact crop yield?
ⓐ. They chemically react with ${CO}_2$, depleting essential nutrients.
ⓑ. They increase soil temperature excessively, killing roots.
ⓒ. They prevent the oxidation of essential micronutrients like iron.
ⓓ. They physically hinder root penetration, reduce soil aeration, and decrease water-holding capacity.
Correct Answer: They physically hinder root penetration, reduce soil aeration, and decrease water-holding capacity.
Explanation: Plastic fragments, especially microplastics, disrupt the natural soil structure. They impede the physical growth of roots, reduce the pore spaces necessary for air exchange (aeration), and interfere with the soil’s ability to absorb and retain water, all of which directly lower crop productivity.
133. Chronic exposure to Cadmium (${Cd}$) from contaminated soil and crops can primarily lead to severe damage and dysfunction in which major organ system?
ⓐ. The respiratory system (Lungs)
ⓑ. The cardiovascular system (Heart)
ⓒ. The renal and skeletal systems (Kidneys and Bones)
ⓓ. The reproductive system
Correct Answer: The renal and skeletal systems (Kidneys and Bones)
Explanation: Cadmium is nephrotoxic (damaging to the kidneys) and osteotoxic (damaging to the bones). Chronic exposure causes kidney failure and leads to bone disorders like osteoporosis and osteomalacia, which were famously observed in the victims of Itai-Itai disease in Japan, resulting from ${Cd}$-contaminated rice.
134. Which adverse effect on agriculture is directly caused by the accumulation of excess salts, often from over-fertilization, in the root zone?
ⓐ. Soil liquefaction
ⓑ. Increased ${pH}$ (alkalization)
ⓒ. Eutrophication
ⓓ. Salinization (leading to osmotic stress and reduced water uptake)
Correct Answer: Salinization (leading to osmotic stress and reduced water uptake)
Explanation: The build-up of soluble salts from fertilizers leads to salinization. High salt concentrations outside the root cells cause the soil solution to have a lower water potential. This creates osmotic stress, drawing water out of the plant roots (plasmolysis) or preventing the plant from absorbing water, effectively causing physiological drought.
135. The long-term presence of certain pesticides in the soil can disrupt the natural biogeochemical cycles, primarily by:
ⓐ. Accelerating the breakdown of lignin and cellulose.
ⓑ. Killing non-target soil microorganisms crucial for nitrogen fixation and organic matter decomposition.
ⓒ. Increasing the natural leaching rate of potassium.
ⓓ. Promoting the growth of parasitic nematodes.
Correct Answer: Killing non-target soil microorganisms crucial for nitrogen fixation and organic matter decomposition.
Explanation: Pesticides are designed to be toxic. When applied to soil, they often kill beneficial, non-target bacteria and fungi that are vital for critical processes like nitrogen fixation (converting atmospheric ${N}_2$ into usable forms) and the decomposition of organic matter, thereby drastically reducing the long-term fertility and health of the soil.
136. Soil pollution by Lead (${Pb}$) poses a major human health threat, especially in children, primarily because it:
ⓐ. Interferes with the development of the central nervous system and brain function.
ⓑ. Attacks red blood cells, causing anemia.
ⓒ. Causes liver cirrhosis.
ⓓ. Leads to acute respiratory failure.
Correct Answer: Interferes with the development of the central nervous system and brain function.
Explanation: Lead is a potent neurotoxin. In children, exposure through contaminated soil, dust, and food significantly impairs the development of the central nervous system and the brain. This can lead to cognitive deficits, reduced ${IQ}$, behavioral problems, and learning disabilities.
137. Soil contamination with radioactive isotopes (e.g., Strontium-90, Caesium-137) poses a long-term risk to human health primarily because these elements:
ⓐ. Chemically destroy the soil’s organic content.
ⓑ. Have short half-lives and decay quickly into toxic metals.
ⓒ. Can be easily inhaled through the dust particles.
ⓓ. Mimic essential elements, allowing them to be readily absorbed by crops and stored in human tissues (bone, muscle).
Correct Answer: Mimic essential elements, allowing them to be readily absorbed by crops and stored in human tissues (bone, muscle).
Explanation: Radioisotopes like Strontium-90 (${Sr-90}$) mimic Calcium and are readily absorbed by crops and stored in human bones. Caesium-137 (${Cs-137}$) mimics Potassium and is stored in muscle tissue. This ability to biomimic essential elements allows them to persist and accumulate in the body, continuously irradiating tissues and increasing the risk of cancer.
138. The use of certain persistent herbicides in agriculture can damage the soil by:
ⓐ. Causing a massive increase in the population of beneficial earthworms.
ⓑ. Creating highly acidic microenvironments around the root zones.
ⓒ. Chemically binding with Carbon Dioxide, enriching the soil.
ⓓ. Preventing the leaching of excess salts.
Correct Answer: Creating highly acidic microenvironments around the root zones.
Explanation: While all pesticides can be harmful, some soil contaminants, including certain nitrogenous fertilizers and their degradation products, contribute to soil acidification. This reduction in ${pH}$ creates toxic microenvironments that hinder nutrient availability and plant health, an effect sometimes linked to the microbial processing of chemical contaminants.
139. The most significant way soil pollution contributes to water-borne diseases in the local human population is by:
ⓐ. Making the water taste salty.
ⓑ. Reducing the total amount of available irrigation water.
ⓒ. Acting as a reservoir for pathogens and transporting them to groundwater and surface water via runoff or infiltration.
ⓓ. Causing fish kills that contaminate drinking sources.
Correct Answer: Acting as a reservoir for pathogens and transporting them to groundwater and surface water via runoff or infiltration.
Explanation: Soil, especially when polluted by sewage sludge or animal waste, acts as a temporary reservoir for human and animal pathogens (bacteria, viruses, parasites). Rain and irrigation then wash these pathogens from the soil surface into surface streams (runoff) or allow them to seep into groundwater (infiltration), contaminating the community’s water sources and leading to outbreaks of diseases like cholera and dysentery.
140. Which specific agricultural effect results from the low ${pH}$ conditions caused by soil pollution, leading to the dissolution of aluminum from clay minerals?
ⓐ. Aluminum toxicity (stunting root growth) N
ⓑ. Nitrogen fixation inhibition
ⓒ. utrient immobilization (making nutrients unavailable)
ⓓ. Increased fungal resistance
Correct Answer: Aluminum toxicity (stunting root growth)
Explanation: When soil ${pH}$ drops below $\sim 5.0$ due to pollution (e.g., acid rain or excessive nitrogen fertilizer), aluminum (${Al}$), which is normally bound in clay minerals, becomes soluble as highly toxic ${Al}^{3+}$ ions. These ions are extremely damaging to plant roots, inhibiting their elongation and nutrient absorption, which severely limits crop yield.
141. Fly ash is a common type of solid waste generated by which major industrial sector?
ⓐ. Petroleum refining
ⓑ. Nuclear power generation
ⓒ. Thermal power plants (coal burning)
ⓓ. Pharmaceutical manufacturing
Correct Answer: Thermal power plants (coal burning)
Explanation: Fly ash is a finely divided residue resulting from the combustion of pulverized coal in thermal power plants. It is one of the largest volumes of industrial solid waste generated globally. It is typically hazardous due to the presence of trace heavy metals.
142. The term industrial effluent specifically refers to which type of industrial waste?
ⓐ. Liquid wastewater discharged from industrial processes
ⓑ. Solid residue from smelting operations
ⓒ. Gaseous emissions from tall smokestacks
ⓓ. Highly pressurized steam condensate
Correct Answer: Liquid wastewater discharged from industrial processes
Explanation: Industrial effluent is the general term for the outflow of water-based waste from industrial and manufacturing facilities. These liquids often contain a complex mix of chemical pollutants, heat, and suspended solids, posing a severe risk to aquatic ecosystems.
143. Gaseous industrial waste is primarily released through which infrastructure component?
ⓐ. Sludge drying beds
ⓑ. Smokestacks or chimney vents
ⓒ. Effluent storage ponds
ⓓ. Landfill caps
Correct Answer: Smokestacks or chimney vents
Explanation: Gaseous pollutants—such as oxides of nitrogen (${NO}_{{x}}$), sulphur dioxide (${SO}_2$), and volatile organic compounds (${VOCs}$)—are typically products of combustion or chemical reactions and are released into the atmosphere via tall smokestacks or exhaust vents.
144. Slag, a solid residue formed during the separation of the metal from the original ore in smelting, is classified as which type of industrial waste?
ⓐ. Municipal solid waste
ⓑ. Non-hazardous liquid waste
ⓒ. Low-level radioactive waste
ⓓ. Non-hazardous heavy solid waste
Correct Answer: Non-hazardous heavy solid waste
Explanation: Slag is a byproduct of metallurgical processes. While generally classified as non-hazardous, it is dense, bulky, and generated in enormous volumes, making its safe disposal and utilization a significant challenge for the metal industry.
145. Organic load (high ${BOD}$ and ${COD}$) and toxic, non-biodegradable synthetic chemicals (e.g., dyes, solvents) are the primary contaminants in the liquid effluent from which industrial sector?
ⓐ. Pharmaceuticals, textiles, and organic chemical manufacturing
ⓑ. Cement and construction material production
ⓒ. Nuclear power plants
ⓓ. Food processing and dairy production
Correct Answer: Pharmaceuticals, textiles, and organic chemical manufacturing
Explanation: Industries involved in synthesizing complex organic compounds, such as pharmaceuticals and textile dyeing, generate wastewater rich in complex, often refractory (hard to degrade) organic chemicals and solvents, contributing significantly to the ${COD}$ (Chemical Oxygen Demand) of the effluent.
146. A major component of gaseous industrial waste from the cement industry, contributing to both air pollution and greenhouse effects, is:
ⓐ. Sulphur Dioxide (${SO}_2$)
ⓑ. Hydrochloric Acid (${HCl}$)
ⓒ. Carbon Dioxide (${CO}_2$) and Particulate Matter (${PM}$)
ⓓ. Methane (${CH}_4$)
Correct Answer: Carbon Dioxide (${CO}_2$) and Particulate Matter (${PM}$)
Explanation: The cement industry is a major source of pollution. ${CO}_2$ is released both from the combustion of fuel and the calcination (heating) of limestone (${CaCO}_3$). Particulate Matter is also released from the kiln operations, contributing to local air quality issues.
147. Heavy metal sludge (a semi-solid, viscous waste) containing high concentrations of ${Cr}, {Ni}, {Zn}$, and ${Cd}$ is the characteristic solid waste from which type of operation?
ⓐ. Food processing and canning
ⓑ. Paper and pulp mills
ⓒ. Metal plating (electroplating) and surface finishing
ⓓ. Oil and gas drilling
Correct Answer: Metal plating (electroplating) and surface finishing
Explanation: Electroplating and metal finishing processes use solutions containing various heavy metals. The removal of these metals from the wastewater during treatment (e.g., precipitation) results in the formation of a toxic sludge that must be treated as hazardous solid waste.
148. The large volume of concentrated saline water known as brine, which is discharged and affects the salinity of coastal waters, is a type of industrial liquid waste generated primarily by:
ⓐ. Petroleum refineries
ⓑ. Textile processing plants
ⓒ. Sugar mills
ⓓ. Desalination plants
Correct Answer: Desalination plants
Explanation: Desalination plants (used to turn seawater into drinking water) produce highly concentrated salt solutions, or brine, as a byproduct. Discharging this brine into coastal waters can locally increase salinity and temperature, stressing marine ecosystems.
149. ${Particulate Matter}$ (${PM}$) like smoke, dust, and aerosols released from industrial smokestacks is categorized as which type of gaseous pollutant?
ⓐ. Primary pollutant
ⓑ. Secondary pollutant
ⓒ. Stable pollutant
ⓓ. Volatile organic compound (${VOC}$)
Correct Answer: Primary pollutant
Explanation: Primary pollutants are those emitted directly into the atmosphere from an identifiable source, such as a factory smokestack. ${PM}$ is released directly as a result of combustion or grinding processes, classifying it as a primary pollutant, unlike secondary pollutants like ozone (${O}_3$), which form through atmospheric reactions.
150. Which characteristic is generally true for the liquid and gaseous waste generated by the industrial sector compared to municipal waste?
ⓐ. They are typically generated in smaller total volumes.
ⓑ. They often contain a higher concentration of toxic, non-biodegradable, or persistent pollutants.
ⓒ. They are always easier and cheaper to treat.
ⓓ. They are mainly comprised of simple, easily degradable organic compounds.
Correct Answer: They often contain a higher concentration of toxic, non-biodegradable, or persistent pollutants.
Explanation: Industrial processes concentrate chemicals and use materials that are inherently toxic (heavy metals, organic solvents, acids). Thus, industrial liquid and gaseous wastes are typically characterized by a much higher concentration and complexity of dangerous, persistent, and non-biodegradable contaminants compared to the largely organic and biodegradable nature of municipal waste.
151. Which waste disposal method is considered the preferred choice for hazardous liquid industrial waste as it permanently isolates the waste in deep, porous rock formations?
ⓐ. Deep-well injection
ⓑ. Ocean dumping
ⓒ. Open burning
ⓓ. Sanitary landfilling
Correct Answer: Deep-well injection
Explanation: Deep-well injection involves injecting pre-treated hazardous liquid waste into deep, isolated underground rock layers far below the water table, effectively preventing the contamination of soil and usable groundwater. This method is highly regulated and used as a permanent containment strategy for liquids.
152. For high-volume, low-hazard solid industrial waste (like construction debris or fly ash), the most common and economically viable disposal method, provided it meets environmental standards, is:
ⓐ. Incineration
ⓑ. Sanitary Landfilling
ⓒ. Biological treatment (bioremediation)
ⓓ. Plasma gasification
Correct Answer: Sanitary Landfilling
Explanation: Sanitary landfills are engineered disposal sites used for non-hazardous solid waste. When properly designed with liners and leachate collection systems, they provide a safe and cost-effective method for handling the large volumes of solid waste generated by industries.
153. A chemical treatment process used to neutralize highly acidic or basic liquid industrial waste (effluents) before discharge or further treatment is:
ⓐ. Flotation
ⓑ. Sedimentation
ⓒ. Neutralization (acid-base reaction)
ⓓ. Reverse osmosis
Correct Answer: Neutralization (acid-base reaction)
Explanation: Many industrial effluents are highly corrosive due to extreme ${pH}$. Neutralization is a common and necessary primary treatment step where acids or bases are added to adjust the ${pH}$ to a near-neutral level (typically ${pH} 6.0$ to $9.0$) to protect subsequent treatment processes and the receiving environment.
154. Incineration is a high-temperature thermal treatment method often used for hazardous solid or semi-solid industrial waste. The primary advantage of this method is:
ⓐ. Significant reduction in waste volume and weight
ⓑ. Low capital and operating costs
ⓒ. Complete elimination of all gaseous emissions
ⓓ. Recovery of all heavy metals in pure form
Correct Answer: Significant reduction in waste volume and weight
Explanation: Incineration achieves a massive reduction in the physical volume (up to $90\%$) and mass of solid waste, turning the organic components into ash and gas. This drastically reduces the space required for final disposal in a landfill.
155. Which disposal method for gaseous industrial waste involves passing the gas through a liquid (often water or an alkaline solution) to remove pollutants like ${SO}_2$ and ${HCl}$?
ⓐ. Electrostatic precipitation
ⓑ. Catalytic conversion
ⓒ. Adsorption
ⓓ. Wet scrubbing (flue gas desulfurization)
Correct Answer: Wet scrubbing (flue gas desulfurization)
Explanation: Wet scrubbing is a common technology used, especially in coal power plants and large industries. The flue gas is sprayed with a liquid, which physically removes particulates and chemically absorbs acidic gases (${SO}_2$ and ${HCl}$), a process often called flue gas desulfurization (${FGD}$).
156. The use of microorganisms (bacteria, fungi) to break down or detoxify hazardous organic contaminants in contaminated soil or liquid industrial waste is known as:
ⓐ. Phytoremediation
ⓑ. Bioremediation
ⓒ. Chemical precipitation
ⓓ. Thermal desorption
Correct Answer: Bioremediation
Explanation: Bioremediation is an environmentally friendly disposal/cleanup technique that relies on naturally occurring or engineered microbes to metabolize and transform complex, hazardous organic substances into simpler, less toxic compounds like ${CO}_2$ and water.
157. Which highly specialized and expensive disposal method is mandated for high-level radioactive waste due to its long-term toxicity and extremely long half-life?
ⓐ. Geological repository (deep underground disposal)
ⓑ. Simple near-surface burial
ⓒ. Ocean dilution and disposal
ⓓ. Incineration at ultra-high temperatures
Correct Answer: Geological repository (deep underground disposal)
Explanation: High-level radioactive waste requires permanent isolation from the biosphere for tens of thousands of years. The only internationally accepted long-term disposal method is emplacement in a deep geological repository, typically in stable rock formations several hundred meters below the surface.
158. A process used to treat liquid waste containing high concentrations of dissolved heavy metals, where a chemical agent is added to convert the soluble metal ions into insoluble compounds that can be filtered out, is:
ⓐ. Ion exchange
ⓑ. Reverse osmosis
ⓒ. Chemical precipitation
ⓓ. ${UV}$ disinfection
Correct Answer: Chemical precipitation
Explanation: Chemical precipitation is a conventional method for removing heavy metals from wastewater. It involves adjusting the ${pH}$ and adding a precipitating agent (e.g., lime or sodium hydroxide) to convert the soluble metal ions into an insoluble solid form (a sludge) that can be easily separated from the liquid.
159. For gaseous pollutants, the disposal method that involves passing the gas through a solid material (e.g., activated carbon) to trap the chemical compounds on its large surface area is:
ⓐ. Wet scrubbing
ⓑ. Thermal oxidation
ⓒ. Catalytic conversion
ⓓ. Adsorption
Correct Answer: Adsorption
Explanation: Adsorption is a physical process where molecules of the gaseous pollutant are attracted to and held onto the surface of a solid material (the adsorbent), such as activated carbon or specialized resins. This is highly effective for removing ${VOCs}$ (Volatile Organic Compounds) and odors from gaseous streams.
160. Before disposal, hazardous liquid industrial waste is often stabilized and solidified by mixing it with materials like cement or lime. This pre-disposal method is known as:
ⓐ. Thermal desorption
ⓑ. Air stripping
ⓒ. Solidification/Stabilization
ⓓ. Biological degradation
Correct Answer: Solidification/Stabilization
Explanation: Solidification/Stabilization is a process that physically encapsulates the contaminants within a solid matrix (e.g., cement or concrete) or chemically alters them to reduce their solubility and mobility. This makes the waste safer for transportation and final placement in a landfill or repository.
161. The core principle of waste minimization in industrial operations is best described by which strategy?
ⓐ. Source reduction: preventing the generation of waste in the first place
ⓑ. Finding new landfills for toxic waste disposal
ⓒ. Treating waste aggressively before discharge
ⓓ. Using waste as fuel to generate energy
Correct Answer: Source reduction: preventing the generation of waste in the first place
Explanation: Waste minimization adheres to the “reduce” principle, prioritizing changes in industrial practices, input materials, or technology to prevent the creation of waste at the source, which is the most environmentally and economically effective solution.
162. Recycling a material back into the production process after it has served its original purpose is categorized as which type of pollution control measure?
ⓐ. End-of-pipe treatment
ⓑ. Resource conservation and recovery
ⓒ. Waste dilution
ⓓ. Primary material extraction
Correct Answer: Resource conservation and recovery
Explanation: Recycling falls under resource management, where materials that would otherwise be discarded are recovered and reprocessed, thereby conserving natural resources, reducing energy use, and minimizing the need for disposal.
163. The industrial strategy of using the waste product from one manufacturing process as a raw material in a different industrial process (e.g., using fly ash in cement production) is called:
ⓐ. Direct dumping
ⓑ. Product redesign
ⓒ. Industrial symbiosis (or Waste Exchange)
ⓓ. Material substitution
Correct Answer: Industrial symbiosis (or Waste Exchange)
Explanation: Industrial symbiosis describes a collaborative approach where one industry’s waste stream is effectively fed into another industry as a valuable input, creating a closed-loop system that maximizes resource efficiency and minimizes overall waste generation.
164. What is the primary environmental benefit of industrial recycling over landfill disposal?
ⓐ. Increased tax revenue for local governments
ⓑ. Creation of more jobs in the disposal sector
ⓒ. Reduced regulatory oversight for the industry
ⓓ. Conservation of non-renewable resources and reduced energy consumption
Correct Answer: Conservation of non-renewable resources and reduced energy consumption
Explanation: Recycling significantly reduces the demand for virgin materials, conserving natural resources. Furthermore, processing secondary materials often requires substantially less energy than extracting and refining new raw materials (e.g., aluminum from scrap vs. bauxite ore).
165. Which waste minimization technique focuses on changing the raw materials or process steps to reduce the volume or toxicity of the waste stream at the source?
ⓐ. Process modification and material substitution
ⓑ. Enhanced scrubber technology
ⓒ. Advanced biological treatment
ⓓ. Deep-well injection
Correct Answer: Process modification and material substitution
Explanation: Process modification involves changing operating parameters or equipment, while material substitution replaces hazardous inputs with non-hazardous or less toxic alternatives. Both are “at-the-source” methods aimed at preventing waste generation.
166. A major challenge in recycling mixed industrial plastic waste compared to consumer plastic waste is:
ⓐ. The higher density of industrial plastics
ⓑ. The use of natural organic colorants
ⓒ. The high variability in polymer type and chemical contaminants
ⓓ. The large size of the plastic sheets
Correct Answer: The high variability in polymer type and chemical contaminants
Explanation: Industrial plastic waste is often a complex mixture of different polymer types (e.g., ${PVC}$, ${HDPE}$, ${PET}$) that are difficult to separate, and they may be contaminated with chemical residues, solvents, or additives, making clean and pure recycling difficult and less cost-effective.
167. Which term describes the complete recovery of energy from industrial organic waste material through controlled combustion (such as burning waste solvents or biomass for heat or electricity)?
ⓐ. Primary material reuse
ⓑ. Waste-to-Energy (WTE) or Energy Recovery
ⓒ. Biological waste treatment
ⓓ. Detoxification
Correct Answer: Waste-to-Energy (WTE) or Energy Recovery
Explanation: Waste-to-Energy is a recovery method that utilizes the chemical energy contained in combustible waste (organic solids, liquids, or gases) by burning them in specialized incinerators to produce steam or electricity, displacing the need for fossil fuels.
168. The industrial concept that emphasizes designing products for easier reuse, repair, and recyclability at the end of their life cycle is known as:
ⓐ. Waste stream consolidation
ⓑ. Resource optimization
ⓒ. Zero discharge manufacturing
ⓓ. Design for Environment (DfE) or Eco-Design
Correct Answer: Design for Environment (DfE) or Eco-Design
Explanation: Design for Environment is a proactive approach that integrates environmental considerations into every stage of product development, ensuring products are made with minimal material, last longer, and can be easily disassembled and recycled after their useful life.
169. Closed-loop recycling for industrial wastewater is a waste minimization technique that achieves:
ⓐ. Maximum reuse of treated wastewater within the same facility with minimal external discharge
ⓑ. Transfer of wastewater to another factory for their use
ⓒ. Complete neutralization of all heavy metals
ⓓ. Conversion of wastewater into solid sludge
Correct Answer: Maximum reuse of treated wastewater within the same facility with minimal external discharge
Explanation: In a closed-loop system, industrial wastewater is treated to meet specific quality standards and is then channeled back into the factory process for reuse, thereby drastically reducing both water consumption and the volume of effluent discharged.
170. Which element of waste management aligns most closely with the “reduce” principle of waste minimization?
ⓐ. Packaging reduction and material light-weighting
ⓑ. Converting waste into usable compost
ⓒ. Optimizing batch size and improving inventory control to prevent spoilage
ⓓ. Selling byproduct materials for profit
Correct Answer: Optimizing batch size and improving inventory control to prevent spoilage
Explanation: Improving internal operations, such as optimizing process control and inventory management, directly prevents raw material and product spoilage, which is a form of waste. This preventative action is the core of the “reduce” principle at the industrial source.
171. The primary function of a three-way catalytic converter in a gasoline engine vehicle is to treat which three main pollutants simultaneously?
ⓐ. Carbon Monoxide (${CO}$), Nitrogen Oxides (${NO}_{{x}}$), and Hydrocarbons (${HC}$)
ⓑ. Sulphur Dioxide (${SO}_2$), Particulate Matter (${PM}$), and Methane (${CH}_4$)
ⓒ. Carbon Dioxide (${CO}_2$), Water Vapor (${H}_2{O}$), and Lead (${Pb}$)
ⓓ. Chlorofluorocarbons (${CFCs}$), Ozone (${O}_3$), and Formaldehyde
Correct Answer: Carbon Monoxide (${CO}$), Nitrogen Oxides (${NO}_{{x}}$), and Hydrocarbons (${HC}$)
Explanation: A three-way catalytic converter is named for its ability to simultaneously catalyze three reactions: oxidation of ${CO}$ and ${HC}$ (unburnt fuel) and reduction of ${NO}_{{x}}$. The goal is to convert all three into less harmful substances like ${CO}_2$, ${H}_2{O}$, and ${N}_2$.
172. Which of the following is the primary gaseous pollutant released from petrol and diesel vehicles that contributes to the formation of ground-level ozone and photochemical smog?
ⓐ. Carbon Monoxide (${CO}$)
ⓑ. Sulphur Dioxide (${SO}_2$)
ⓒ. Carbon Dioxide (${CO}_2$)
ⓓ. Nitrogen Oxides (${NO}_{{x}}$)
Correct Answer: Nitrogen Oxides (${NO}_{{x}}$)
Explanation: Nitrogen Oxides (${NO}_{{x}}$), particularly ${NO}$ and ${NO}_2$, are formed under the high pressure and high temperature conditions inside the engine cylinder. In the atmosphere, they react with ${VOCs}$ (Hydrocarbons) in the presence of sunlight to form photochemical smog and ground-level ozone (${O}_3$).
173. Compressed Natural Gas (${CNG}$) is often preferred over conventional gasoline or diesel as a fuel for public transport because it produces significantly lower emissions of:
ⓐ. Carbon Dioxide (${CO}_2$) per unit of energy
ⓑ. Total thermal energy
ⓒ. Sulphur dioxide (${SO}_2$) and particulate matter (${PM}$)
ⓓ. Nitrogen Oxides (${NO}_{{x}}$)
Correct Answer: Sulphur dioxide (${SO}_2$) and particulate matter (${PM}$)
Explanation: ${CNG}$ is primarily methane (${CH}_4$). Because it contains almost no sulphur and burns cleaner than diesel, its combustion results in negligible emissions of sulphur dioxide (${SO}_2$) and particulate matter (${PM}$), making it a much cleaner alternative for air quality.
174. The catalytic action in a three-way converter relies on precious metals coated onto a ceramic or metallic honeycomb structure. Which combination of metals is typically used?
ⓐ. Platinum (${Pt}$), Palladium (${Pd}$), and Rhodium (${Rh}$)
ⓑ. Iron (${Fe}$), Nickel (${Ni}$), and Copper (${Cu}$)
ⓒ. Silver (${Ag}$), Gold (${Au}$), and Zinc (${Zn}$)
ⓓ. Aluminum (${Al}$), Silicon (${Si}$), and Titanium (${Ti}$)
Correct Answer: Platinum (${Pt}$), Palladium (${Pd}$), and Rhodium (${Rh}$)
Explanation: Platinum and Palladium act as oxidation catalysts (converting ${CO}$ and ${HC}$ to ${CO}_2$ and ${H}_2{O}$), while Rhodium acts as the reduction catalyst (converting ${NO}_{{x}}$ to ${N}_2$ and ${O}_2$).
175. The use of leaded gasoline was phased out globally primarily because lead compounds:
ⓐ. Caused the engine to seize due to increased friction.
ⓑ. Poisoned and deactivated the catalysts (e.g., Platinum) in the catalytic converters.
ⓒ. Increased the viscosity of the motor oil.
ⓓ. Reduced the fuel efficiency of the vehicle.
Correct Answer: Poisoned and deactivated the catalysts (e.g., Platinum) in the catalytic converters.
Explanation: Lead, used as an anti-knock agent, deposited on the surface of the catalyst materials (${Pt}, {Pd}, {Rh}$) in the converter. This coating prevented the exhaust gases from reacting with the catalyst, rendering the expensive emission control device useless—a process known as catalyst poisoning.
176. The Exhaust Gas Recirculation (${EGR}$) system is an emission control technology used to reduce which specific pollutant?
ⓐ. Carbon Monoxide (${CO}$)
ⓑ. Particulate Matter (${PM}$)
ⓒ. Nitrogen Oxides (${NO}_{{x}}$)
ⓓ. Unburnt Hydrocarbons (${HC}$)
Correct Answer: Nitrogen Oxides (${NO}_{{x}}$)
Explanation: ${NO}_{{x}}$ formation is highly dependent on high combustion temperatures. The ${EGR}$ system works by recirculating a portion of the inert exhaust gas back into the combustion chamber, which lowers the peak combustion temperature, thereby effectively suppressing the formation of ${NO}_{{x}}$.
177. Emission standards, such as India’s Bharat Stage (BS) norms or Europe’s Euro standards, aim primarily to control the quantity of:
ⓐ. Pollutants (${HC}, {CO}, {NO}_{{x}}, {PM}$) emitted per kilometer traveled
ⓑ. Gasoline consumed per vehicle
ⓒ. ${CO}_2$ emitted as a greenhouse gas
ⓓ. Water vapor produced by combustion
Correct Answer: Pollutants (${HC}, {CO}, {NO}_{{x}}, {PM}$) emitted per kilometer traveled
Explanation: These standards are regulatory frameworks that define the acceptable limits for the release of specific criteria air pollutants (${CO}, {HC}, {NO}_{{x}}, {PM}$) from vehicles. The limits are measured in grams of pollutant per kilometer (${g}{/km}$) or equivalent standards.
178. In the reduction stage of the catalytic converter, which two products are formed when nitrogen oxides (${NO}_{{x}}$) are treated?
ⓐ. ${CO}_2$ and ${H}_2{O}$
ⓑ. ${CO}$ and ${O}_3$
ⓒ. ${Nitrogen gas}$ (${N}_2$) and ${Oxygen gas}$ (${O}_2$)
ⓓ. Ammonia (${NH}_3$) and Nitrous Oxide (${N}_2{O}$)
Correct Answer: ${Nitrogen gas}$ (${N}_2$) and ${Oxygen gas}$ (${O}_2$)
Explanation: The reduction catalyst (Rhodium) converts ${NO}_{{x}}$ into the harmless atmospheric gases: $2{NO} \rightarrow {N}_2 + {O}_2$. This is the crucial step that mitigates the formation of acid rain and smog precursors.
179. A common system used to reduce the emission of unburnt Hydrocarbons (${HC}$) / ${VOCs}$ from the fuel tank and carburetor (evaporative emissions) is the:
ⓐ. ${EGR}$ system
ⓑ. Selective Catalytic Reduction (${SCR}$)
ⓒ. Particulate trap
ⓓ. Canister (or Carbon Canister)
Correct Answer: Canister (or Carbon Canister)
Explanation: The Carbon Canister system (or ${EVAP}$ system) captures the fuel vapors that evaporate from the fuel system using activated carbon. These trapped vapors are later purged and burned in the engine, preventing their release into the atmosphere.
180. The primary advantage of replacing fossil fuel vehicles with electric vehicles (${EVs}$) in terms of air quality control is the elimination of:
ⓐ. The need for specialized batteries
ⓑ. Tailpipe emissions (local pollutants) in urban areas
ⓒ. Traffic congestion
ⓓ. The demand for renewable energy sources
Correct Answer: Tailpipe emissions (local pollutants) in urban areas
Explanation: ${EVs}$ do not have internal combustion engines and thus produce zero tailpipe emissions (${CO}, {HC}, {NO}_{{x}}, {PM}$). This shift significantly improves local air quality, particularly in densely populated urban centers, although the source of electricity generation must be considered for the overall environmental impact.
181. Which common industrial pollution control device is designed to remove particulate matter (${PM}$) from the exhaust gas stream by using an electrical charge to attract the particles to collection plates?
ⓐ. Venturi Scrubber
ⓑ. Cyclone Separator
ⓒ. Baghouse Filter
ⓓ. Electrostatic Precipitator (${ESP}$)
Correct Answer: Electrostatic Precipitator (${ESP}$)
Explanation: The ${ESP}$ charges the ${PM}$ in the gas stream using high voltage, causing the charged particles to migrate toward grounded collecting plates, where they adhere and are periodically shaken loose into a hopper.
182. A cyclone separator (or cyclone collector) is primarily used in industries to remove which type of pollutant from a gaseous stream?
ⓐ. Gaseous ${SO}_2$
ⓑ. Fine aerosols and mists
ⓒ. Relatively coarse particulate matter
ⓓ. ${VOCs}$ (Volatile Organic Compounds)
Correct Answer: Relatively coarse particulate matter
Explanation: Cyclone separators work by creating a vortex flow. Centrifugal force pushes heavier, coarse ${PM}$ particles outward toward the collector walls, allowing them to fall to a hopper, making them highly effective for separating larger, denser dust particles.
183. Which industrial control technology works by passing exhaust gases through a fabric structure, essentially acting like a giant vacuum cleaner to trap fine particulates?
ⓐ. Electrostatic Precipitator (${ESP}$)
ⓑ. Baghouse filter (or Fabric Filter)
ⓒ. Wet Scrubber
ⓓ. Activated Carbon Adsorber
Correct Answer: Baghouse filter (or Fabric Filter)
Explanation: A Baghouse uses multiple parallel fabric bags (or cartridges) to physically filter particulates from the gas stream. The accumulating dust layer on the fabric surface actually enhances the filtration efficiency for very fine particles.
184. Wet scrubbers are highly effective for removing both gaseous pollutants and particulate matter. The removal of gaseous pollutants (${SO}_2, {HCl}$) is achieved primarily through:
ⓐ. Chemical absorption and reaction with the scrubbing liquid
ⓑ. High-velocity centrifugal separation
ⓒ. Mechanical filtration by the scrubber nozzle
ⓓ. Thermal oxidation in the scrubber chamber
Correct Answer: Chemical absorption and reaction with the scrubbing liquid
Explanation: When the exhaust gas comes into contact with the scrubbing liquid (often water or a lime slurry), the soluble or reactive acidic gases like ${SO}_2$ are chemically absorbed or neutralized by the liquid, removing them from the gas stream.
185. In industrial processes, a catalytic converter is most frequently used to eliminate which major class of air pollutants?
ⓐ. Particulate matter (${PM}$)
ⓑ. Heavy metal vapor
ⓒ. Volatile Organic Compounds (${VOCs}$) and ${CO}$
ⓓ. Acid mists (${H}_2{SO}_4$)
Correct Answer: Volatile Organic Compounds (${VOCs}$) and ${CO}$
Explanation: Industrial catalytic converters (often called catalytic oxidizers) are used to convert ${VOCs}$ (unburnt hydrocarbons/solvents) and ${CO}$ into harmless ${CO}_2$ and ${H}_2{O}$ by accelerating the oxidation reaction at a lower temperature than thermal oxidizers.
186. To eliminate low concentrations of hazardous Volatile Organic Compounds (${VOCs}$) in a gaseous emission stream, the most efficient physical removal process is:
ⓐ. Adsorption (using activated carbon)
ⓑ. Wet scrubbing
ⓒ. Combustion
ⓓ. Flocculation
Correct Answer: Adsorption (using activated carbon)
Explanation: Adsorption involves passing the gas stream over a solid material, typically activated carbon, which has an extremely large surface area. The ${VOC}$ molecules are physically attracted to and trapped on the surface, making this an ideal solution for low-concentration pollutant removal.
187. Which process is an end-of-pipe treatment method for liquid industrial waste that physically separates solid particles from the water by allowing them to settle out under gravity?
ⓐ. Neutralization
ⓑ. Reverse Osmosis (${RO}$)
ⓒ. Flotation
ⓓ. Sedimentation (or Clarification)
Correct Answer: Sedimentation (or Clarification)
Explanation: Sedimentation is a primary physical treatment step where the velocity of the liquid waste is slowed down in a large basin, allowing suspended solids, grit, and larger particles to settle to the bottom under the influence of gravity.
188. Thermal oxidation (or Afterburners) is an industrial control method that treats gaseous waste by:
ⓐ. Cooling the gas to condense the pollutants.
ⓑ. Heating the gas stream to high temperatures to chemically destroy organic pollutants.
ⓒ. Adding a catalyst to convert ${NO}_{{x}}$ to ${N}_2$.
ⓓ. Injecting steam to humidify and dissolve the ${PM}$.
Correct Answer: Heating the gas stream to high temperatures to chemically destroy organic pollutants.
Explanation: Thermal oxidizers rely on high temperatures (up to $1000^{\circ}{C}$) to burn or oxidize ${VOCs}$ and other hazardous organic air pollutants, converting them into non-toxic ${CO}_2$ and water vapor.
189. A membrane filtration process used in liquid industrial waste treatment that separates even dissolved salts and small organic molecules from water under pressure is:
ⓐ. Ultrafiltration
ⓑ. Microfiltration
ⓒ. Reverse Osmosis (${RO}$)
ⓓ. Granular Media Filtration
Correct Answer: Reverse Osmosis (${RO}$)
Explanation: Reverse Osmosis (${RO}$) is a high-pressure membrane process capable of removing the smallest dissolved contaminants, including inorganic salts, ions, and low-molecular-weight organics, making it a critical tertiary treatment for producing high-purity process water or final effluent polishing.
190. Which industrial air pollution control method for ${PM}$ involves injecting an absorbent material (like lime or activated carbon) into the flue gas stream to react with and capture pollutants, followed by removal in a filter?
ⓐ. Wet Scrubber
ⓑ. Dry Injection or Dry Scrubber
ⓒ. Catalytic Converter
ⓓ. ${EGR}$ system
Correct Answer: Dry Injection or Dry Scrubber
Explanation: Dry injection or Dry scrubbing involves injecting a dry sorbent (e.g., lime or activated carbon) directly into the ductwork. The sorbent reacts with the acid gases or ${Hg}$ and is then collected along with the captured pollutants in a downstream device, such as a ${Baghouse}$ or ${ESP}$.
191. The Water (Prevention and Control of Pollution) Act in India was enacted in which year, establishing regulatory boards to prevent and control water pollution?
ⓐ. 1974
ⓑ. 1981
ⓒ. 1986
ⓓ. 2002
Correct Answer: 1974
Explanation: The Water Act, 1974 was the first major environmental legislation in India, establishing the Central Pollution Control Board (${CPCB}$) and State Pollution Control Boards (${SPCBs}$) with powers to set standards and prosecute violators.
192. Which international agreement, signed in 1987, is recognized as the most successful treaty in history for phasing out the production of ozone-depleting substances (${ODS}$) like ${CFCs}$?
ⓐ. The Kyoto Protocol
ⓑ. The Paris Agreement
ⓒ. The Vienna Convention
ⓓ. The Montreal Protocol
Correct Answer: The Montreal Protocol
Explanation: The Montreal Protocol on Substances that Deplete the Ozone Layer is a landmark international treaty aimed at protecting the ozone layer by setting mandatory schedules for the phase-out of ${CFCs}$ and ${Halons}$.
193. The Environment (Protection) Act of 1986 was enacted by the Indian Parliament primarily in response to which major industrial disaster?
ⓐ. The Chernobyl disaster (1986)
ⓑ. The Three Mile Island accident (1979)
ⓒ. The Bhopal Gas Tragedy (1984)
ⓓ. The London Great Smog (1952)
Correct Answer: The Bhopal Gas Tragedy (1984)
Explanation: The devastating Bhopal Gas Tragedy highlighted the severe gaps in existing environmental laws and spurred the government to pass the comprehensive Environment (Protection) Act of 1986, which gave the central government broad powers to frame rules and regulations to protect and improve the environment.
194. The National Green Tribunal (${NGT}$) in India was established in 2010 to handle cases related to:
ⓐ. Economic trade disputes only.
ⓑ. Civil and criminal law, excluding environmental issues.
ⓒ. Expeditious disposal of environmental cases and conservation of forests.
ⓓ. Taxation and revenue matters.
Correct Answer: Expeditious disposal of environmental cases and conservation of forests.
Explanation: The ${NGT}$ is a specialized judicial body dedicated solely to hearing civil cases related to environmental protection and the enforcement of environmental laws, ensuring rapid and expert resolution of such disputes.
195. The Polluter Pays Principle is a fundamental tenet of environmental law that holds:
ⓐ. Governments are responsible for all environmental cleanup costs.
ⓑ. The party responsible for causing pollution must bear the costs of its remediation and compensation.
ⓒ. Industries that comply with standards are exempt from all taxes.
ⓓ. Only major corporations, not individuals, can be held liable for environmental damage.
Correct Answer: The party responsible for causing pollution must bear the costs of its remediation and compensation.
Explanation: The Polluter Pays Principle mandates that the cost of pollution prevention, control, and cleanup should be borne by the party that causes the pollution, rather than being externalized to society or the taxpayer.
196. Which Act provides the legal framework for the management, handling, and disposal of hazardous waste in India, controlling waste from generation to final disposal?
ⓐ. The Hazardous Wastes (Management and Handling) Rules, issued under the ${EPA}$
ⓑ. The Forest Conservation Act, 1980
ⓒ. The Wildlife Protection Act, 1972
ⓓ. The Air (Prevention and Control of Pollution) Act, 1981
Correct Answer: The Hazardous Wastes (Management and Handling) Rules, issued under the ${EPA}$
Explanation: The handling of Hazardous Wastes in India is governed by specific rules and regulations established by the Ministry of Environment, Forest and Climate Change (${MoEF}{CC}$) under the umbrella of the ${Environment Protection Act, 1986}$ (${EPA}$).
197. The Air (Prevention and Control of Pollution) Act was passed in which year, giving the ${CPCB}$ and ${SPCBs}$ authority to issue instructions for preventing or restricting air pollution?
ⓐ. 1974
ⓑ. 1981
ⓒ. 1986
ⓓ. 2000
Correct Answer: 1981
Explanation: The Air Act, 1981 extended the regulatory powers of the pollution control boards (established by the Water Act) to include the prevention, control, and abatement of air pollution, allowing them to establish air quality standards and monitor industrial emissions.
198. The primary purpose of conducting an Environmental Impact Assessment (${EIA}$) before starting a large-scale industrial project is to:
ⓐ. Ensure the project is financially profitable for investors.
ⓑ. Obtain clearance from the local municipal council.
ⓒ. Predict and evaluate the potential environmental effects of the project and suggest mitigation measures.
ⓓ. Determine the number of jobs the project will create.
Correct Answer: Predict and evaluate the potential environmental effects of the project and suggest mitigation measures.
Explanation: An ${EIA}$ is a legal requirement in many countries. Its purpose is to systematically analyze the social, economic, and environmental consequences of a proposed development action before a decision is made, ensuring environmental protection is integrated into planning.
199. The concept of Sustainable Development was formalized and popularized by which landmark international report?
ⓐ. Silent Spring (Rachel Carson)
ⓑ. The Limits to Growth (Club of Rome)
ⓒ. The Brundtland Report (Our Common Future)
ⓓ. The Stockholm Declaration
Correct Answer: The Brundtland Report (Our Common Future)
Explanation: Published in 1987, the Brundtland Report officially introduced and defined Sustainable Development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”
200. Which international convention aims to control the transboundary movement of hazardous wastes and their disposal, particularly from developed to less developed countries?
ⓐ. The Kyoto Protocol
ⓑ. The Rotterdam Convention
ⓒ. The Stockholm Convention (on ${POPs}$)
ⓓ. The Basel Convention
Correct Answer: The Basel Convention
Explanation: The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal (1992) seeks to minimize the generation of hazardous waste, control its movement, and ensure its environmentally sound management, especially preventing “toxic colonialism.”
Welcome to Class 11 Chemistry MCQs – Chapter 14: Environmental Chemistry (Part 2). This part continues your learning in environmental chemistry with another 100 MCQs that focus on pollution control, water treatment, and the effects of various chemicals on the environment.
Topics covered in Part 2: Solid waste management, recycling processes, ozone depletion, climate change, and green chemistry practices in industries.
- 👉 This page: Second set of 100 solved MCQs with detailed answers
- 👉 Next: Move to Part 3 for final practice