Search Post on this Blog

Pollution and Pollutants [ Science Set 16] | UPPSC Prelims PYQ of Last 30 Years |Important | Objective Question Answer, MCQ and QUIZ

 1. Which of the following is an indicator of air pollution? ( UPPSC PYQ 2021)

a) Puffballs

b) Algae

c) Lichen

d) Moss

Answer. c) Lichen is not found in air-polluted areas. So, Lichen is an indicator of air pollution. 

Lichen is a combination of Fungi  and Algae

Litmus paper is made up by Rosella lichen. 

The study of Fungi is known as Mycology.

The study of Algae is known as Phycology.

Puffballs are fungi known for their spherical fruiting bodies that release spores when mature. Algae are simple, photosynthetic organisms that can be found in various aquatic habitats. Lichen is a symbiotic relationship between a fungus and an alga or cyanobacterium, forming a unique composite organism. Mosses are small, non-vascular plants that thrive in moist environments. Each of these organisms plays a unique role in their respective ecosystems.

2. "The Ringelmann Scale" is used to measure the density of? ( UPPSC PYQ 2021)

a) Smoke

b) Polluted water

c) Fog

d) Noise

Answer. a) Smoke

"The Ringelmann Scale" is used to measure the density of Smoke. It was developed by a French professor. 

The Ringelmann scale is a method for visually assessing the density or opacity of smoke, air pollution, or other substances that obscure light. It was developed by Maximilien Ringelmann, a French professor of agricultural engineering, in the early 20th century. The scale consists of a series of black and white squares of varying opacity, ranging from 0 (completely transparent) to 5 (completely opaque). Observers use this scale to estimate the density of smoke or emissions by comparing what they see to the squares on the chart. It's a simple and subjective way to gauge the level of air pollution or smoke.

Smoke: Smoke is a collection of airborne solid and liquid particulates and gases emitted when a material undergoes combustion or pyrolysis. It can come from sources like wildfires, industrial processes, and vehicle exhaust. Inhaling smoke can be harmful to human health and contribute to air pollution.

Polluted Water: Polluted water refers to bodies of water (e.g., rivers, lakes, oceans) that have been contaminated by various pollutants, such as chemicals, sewage, heavy metals, or microorganisms. Water pollution can harm aquatic life, make water unsafe for drinking, and have detrimental effects on ecosystems.

Fog: Fog is a natural meteorological phenomenon that consists of tiny water droplets or ice crystals suspended in the air near the Earth's surface. It reduces visibility and can be hazardous for transportation. Fog forms when warm, moist air encounters cooler air, causing the moisture to condense into tiny droplets.

Noise: Noise is defined as an unwanted or disruptive sound. It can come from various sources, including traffic, industrial machinery, construction, and human activities. Prolonged exposure to high levels of noise pollution can lead to hearing damage, stress, and other health issues.

3. Which one of the following gases is used in the manufacturing of Polythene? ( UPPSC PYQ)

a) Ethylene

b) Carbon dioxide

c) Nitrogen

d) Carbon monoxide

Answer. a) Ethylene gases are used in the manufacturing of Polythene.

The manufacturing process of polyethylene typically involves several steps:

Polymerization: Polyethylene is made from ethylene, a hydrocarbon gas. The polymerization process involves breaking the double bond in the ethylene molecules and linking them together to form long chains of polyethylene. This can be done through various methods, including high-pressure polymerization and low-pressure polymerization. 

Feedstock Preparation: Ethylene gas is usually derived from petroleum or natural gas. It undergoes purification processes to remove impurities and is then mixed with a catalyst that initiates polymerization.

Polymerization Reactor: The mixture of ethylene and catalyst is introduced into a polymerization reactor. In the case of high-pressure polymerization, this reactor operates at high temperatures and pressures. 

Cooling and Quenching: After polymerization, the polyethylene is in the form of a hot, molten mass. It is rapidly cooled and quenched to stop the polymerization process and solidify the polyethylene into resin pellets.

Pelletizing: The solidified polyethylene is cut or pelletized into small beads or pellets for ease of handling, transportation, and storage.

Quality Control: The polyethylene pellets undergo quality control checks to ensure they meet the desired specifications, including density, melt flow rate, and other properties.

Packaging and Distribution: The polyethylene pellets are packaged in bags or containers and distributed to manufacturers who will use them to create various plastic products.

Processing into Products: Manufacturers can process polyethylene pellets through various methods like extrusion, injection molding, blow molding, and more to create a wide range of plastic products, including plastic bags, containers, pipes, and films

4. Biological magnification in a food chain is caused by ( UPPSC PYQ)

a) Pesticides

b) Fertilizers

c) Fluorocarbons

d) Sulfur dioxide

Answer. a) Pesticides

Biological magnification in a food chain is caused by Pesticides. 

Biological magnification, also known as biomagnification, is a process that occurs in food chains or food webs where certain harmful substances or pollutants become increasingly concentrated as they move up the trophic levels. This phenomenon is particularly relevant in the context of environmental toxins and pollutants, such as persistent organic pollutants (POPs) and heavy metals. Here's how it works:

Introduction of Pollutants: Pollutants, like pesticides, industrial chemicals, or heavy metals, are introduced into the environment through human activities, such as agriculture, industry, or waste disposal.

Absorption by Producers: These pollutants are often absorbed by primary producers like plants or algae from soil or water.

Transfer to Herbivores: When herbivores (consumers that eat plants) consume these contaminated producers, they take in a small amount of the pollutant. However, since they consume a large volume of plants, the concentration of the pollutants in their bodies remains relatively low.

Transfer to Carnivores: The biomagnification process becomes more pronounced as you move up the food chain. Carnivores that eat herbivores are exposed to a higher concentration of the pollutant because they consume many contaminated herbivores over time.

Top Predators: At the top of the food chain, the apex predators, like large fish, birds, or mammals, may accumulate a significant concentration of the pollutant because they consume many contaminated prey animals during their lifetime. This results in a biomagnified concentration of the pollutant in their tissues.

The key idea is that while the absolute amount of the pollutant may be low in the environment, it becomes increasingly concentrated in organisms at higher trophic levels. This phenomenon can have serious ecological and health implications:

Ecological Impact: Biomagnification can disrupt ecosystems by harming or killing organisms at higher trophic levels. For example, it can lead to the decline of top predator populations.

Health Risks: When humans consume organisms at higher trophic levels, they may be exposed to elevated levels of pollutants, posing health risks. For example, eating large, long-lived fish like tuna can expose humans to high levels of mercury, a heavy metal that biomagnifies in marine food chains.

5. Dry ice is ( UPPSC PYQ)

a) Solid ammonia

b) Solid Sulphur dioxide 

c) Solid carbon dioxide

d) Solid nitrogen

Answer. c) Solid carbon dioxide is also known as Dry ice.

Dry ice is the solid form of carbon dioxide (CO2). It is called "dry ice" because it doesn't melt into a liquid form when it warms up; instead, it undergoes sublimation, transitioning directly from a solid to a gas. Here are some key points about dry ice:

Formation: Dry ice is created by compressing and cooling carbon dioxide gas to very low temperatures, typically below -78.5 degrees Celsius (-109.3 degrees Fahrenheit). At this point, CO2 solidifies into a white, dense substance.

Sublimation: As dry ice warms up or is exposed to higher temperatures, it sublimates, releasing carbon dioxide gas. This process is used for various practical applications, such as creating fog effects or preserving perishable goods.


Special Effects: Dry ice is commonly used in the entertainment industry to create theatrical fog effects in movies, stage productions, and haunted houses.

Shipping and Preservation: It is also used for shipping and preserving frozen or chilled items, like ice cream, vaccines, and biological samples.

Carbonation: Dry ice can be used to carbonate beverages, including making fizzy drinks at home.

Cleaning: In a process called dry ice blasting, solid CO2 pellets are used to clean surfaces by effectively removing dirt and contaminants.

Food and Beverage Service: Some restaurants and bars use dry ice to create dramatic visual effects in cocktails or to keep food items cold.

Safety: Handling dry ice requires caution because it is extremely cold and can cause frostbite upon contact with skin. It should be stored and used in well-ventilated areas to prevent the buildup of carbon dioxide gas, which can displace oxygen in confined spaces.

Environmental Impact: Dry ice is considered an environmentally friendly refrigerant because it does not produce greenhouse gas emissions when it sublimates. However, its production and transportation may have some environmental impacts.

6. Which one of the following pairs is NOT correctly matched ( UPPSC PYQ)

a) Freon: Refrigeration

b) Iodoform: Antiseptic

c) Tri-Nitroglycerine: Explosive

d) Teflon: Gelatin

Answer. d) Teflon: Gelatin; Teflon is Polytetrafluoroethylene or fluoropolymer; commonly used in nonstick coating for cookware.

7. BOD ( Biological Oxygen Demand) is a measure of - ( UPPSC PYQ)

a) Organic matter in water

b) Pathogens present in water

c) Inorganic matter in water

d) Oxygen present in water

Answer. d) Oxygen present in water;

Biological Oxygen Demand (BOD) is a measure of the amount of dissolved oxygen needed by microorganisms in water to break down organic matter, such as sewage, industrial effluent, or decaying plant and animal material. It is a key indicator of the organic pollution level in water bodies and is commonly used to assess water quality. 

Introduction of Organic Matter: When organic substances are discharged into a water body, they serve as a food source for bacteria, fungi, and other microorganisms present in the water.

Microbial Decomposition: These microorganisms consume the organic matter through the process of microbial decomposition, which requires oxygen. During this process, they oxidize the organic compounds, breaking them down into simpler forms.

Oxygen Consumption: As microorganisms consume the organic matter, they also consume dissolved oxygen from the water. This oxygen consumption is what BOD measures.

Interpretation: Higher BOD values indicate a greater amount of organic pollution in the water. Low BOD values suggest that the water has a lower level of organic contamination and is generally cleaner and healthier for aquatic life.

BOD is an important parameter for assessing the impact of wastewater discharges into natural water bodies. Elevated BOD levels can deplete dissolved oxygen in water, leading to hypoxic or anoxic conditions, which can harm aquatic life, disrupt ecosystems, and degrade water quality. Therefore, regulatory agencies often establish BOD limits for effluent discharges to protect water quality and aquatic ecosystems.

8. Which of the following polymers is a biodegradable polymer? ( UPPSC PYQ)

a) Neoprene

b) Nylon 2-Nylon 6

c) Nylon 6, 6

d) Nylon 6

Answer. b) Nylon 2-Nylon 6 is a biodegradable polymer.

Biodegradable polymers, also known as bioplastics or bio-based polymers, are a type of polymer material that can break down naturally in the environment, typically through the action of microorganisms like bacteria and fungi, over time. Unlike traditional plastics, which can persist in the environment for centuries, biodegradable polymers offer the advantage of reduced environmental impact.

Sources: Biodegradable polymers can be derived from various renewable sources, including plants (e.g., starch, cellulose), algae, bacteria (e.g., polyhydroxyalkanoates or PHAs), and even animal proteins (e.g., collagen).

Production: They can be produced through different processes, including fermentation of microorganisms to yield biopolymers or through chemical synthesis using bio-based feedstocks.

Biodegradable polymers are used in applications such as single-use plastics, agricultural films, food packaging, disposable cutlery, medical implants, and more. They are also used in conjunction with traditional plastics to enhance their biodegradability.

9. Which of the following is called "Dry ice"?

a) Anhydrous ice

b) Solid hydrogen peroxide

c) Solid water

d) Solid carbon dioxide

Answer. d) Solid carbon dioxide

10. Dry ice in chemical form is

a) Anhydrous ice

b) Solid hydrogen peroxide

c) Solid water

d) Solid carbon dioxide

Answer. d) Solid carbon dioxide

11. The process used for transforming salty water into pure water is called

a) Deliquescence

b) Efflorescence

c) Electric Separation

d) Reverse Osmosis

Answer. d) Reverse Osmosis;

The process used to transform salty water (usually seawater) into pure water is called desalination. Desalination is crucial in regions where freshwater resources are scarce and can provide a source of clean drinking water, agricultural irrigation, and industrial use. Two common methods for desalination are:

Reverse Osmosis (RO):

In reverse osmosis, salty water is forced through a semi-permeable membrane that allows water molecules to pass through while blocking the salt and other impurities.

Pressure is applied to the salty water to overcome the osmotic pressure and push the water molecules through the membrane.

The result is purified water on one side of the membrane and a concentrated brine solution on the other.

The purified water is collected, and the brine is typically discharged back into the sea.

Multi-Effect Distillation (MED) or Multi-Stage Flash Distillation (MSF):

These methods involve heating the salty water to create water vapor (steam) and then condensing the steam back into liquid water.

Multiple stages or effects are used to increase efficiency. In MED, several evaporators operate at decreasing pressures and temperatures, while in MSF, the process involves flashing the water at multiple stages to create steam.

The distilled water collected from condensation is pure, leaving the salts and impurities behind in the brine.

12. Methane gas-producing field is

a) Wheatfield

b) Paddy field

c) Cotton field

d) Groundnut field

Answer. b) Paddy field

13. CNG used in automobiles to check pollution mainly consists of 

a) CH4

b) CO2

c) N2

d) H3

Answer. a) CH4

14. Which one of the following forms an irreversible complex with hemoglobin in the blood?

a) Carbon dioxide

b) Pure Nitrogen gas

c) Carbon Monoxide

d) A mixture of Carbon Dioxide and Helium

Answer. c) Carbon Monoxide

15. Smokescreen is used in warfare for the purpose of concealment and camouflage. Smoke screens generally consist of fine particles of 

a) Sodium Chloride

b) Silver Iodide

c) Titanium Oxide

d) Magnesium Oxide

Answer. c) Titanium Oxide;

Titanium dioxide (TiO2) is sometimes used in the production of smokescreens, particularly in military applications. It serves several purposes in this context:

White Smoke: Titanium dioxide is a white pigment and is often used to create the white color in smokescreens. When it is dispersed as fine particles in the air, it scatters light and creates a dense, white cloud, which can obscure vision and serve as a smoke screen.

Thermal Screening: In addition to creating a visual barrier, titanium dioxide in smokescreens can also help to obscure thermal radiation. This can make it more challenging for infrared sensors and thermal imaging devices to detect objects or individuals hidden behind the smokescreen.

Visibility Reduction: Smokescreens that contain titanium dioxide can significantly reduce visibility over a wide area, making it harder for adversaries to observe troop movements or military operations.

Particle Size: The size of the titanium dioxide particles can be controlled to influence the properties of the smokescreen. Finer particles may stay suspended in the air longer, creating a more persistent screen, while coarser particles may settle more quickly.

16. Which of the following pairs is correctly matched?

a) Sulfur Dioxide: Teeth

b) Fluoride Pollution: Bhopal Gas Tragedy

c) Methyl Isocyanate: Acid rain 

d) Ozone Depletion: Skin Cancer

Answer. d) Ozone Depletion: Skin Cancer

17. Which one of the following pairs is correctly matched? ( UPPSC PYQ)

a) Biodegradable waste- Chlorofluorocarbon

b) Ozone Depletion- Protection from UV rays

c) Ecosystem- Solar energy

d) Biodegradable -Polythene

Answer. c) Ecosystem- Solar energy

18. What is PH value of pure water? ( UPPSC PYQ)

a) 7.0

b) 6.0

c) 8.0

d) 9.0

Answer. a) 7.0

19. The test to determine the residual free-chlorine in water is ( UPPSC PYQ)

a) Schick test

b) Catalase test

c) Oxidase test

d) Ortho-toluidine test

Answer. d) Ortho-toluidine test is used to determine the residual free-chlorine in water.

Schick Test: The Schick test, also known as the diphtheria skin test, is a test used to determine a person's susceptibility to diphtheria, a bacterial infection caused by Corynebacterium diphtheriae.

Catalase Test: The catalase test is a biochemical test used to identify bacteria that produce the enzyme catalase. 

Oxidase Test: The oxidase test is used to identify bacteria that contain the enzyme cytochrome c oxidase, which is involved in the electron transport chain of aerobic respiration.

20. Which gas is responsible for global warming? ( UPPSC PYQ)

a) Carbon monoxide

b) Carbon dioxide

c) Nitrous oxide

d) Sulfur dioxide

Answer. b) Carbon dioxide;

Several greenhouse gases contribute to global warming by trapping heat in the Earth's atmosphere, leading to an increase in global temperatures. The most significant greenhouse gases responsible for global warming include:

Carbon Dioxide (CO2): Carbon dioxide is the most well-known greenhouse gas and the primary contributor to global warming. It is released into the atmosphere through activities like burning fossil fuels (coal, oil, and natural gas), deforestation, and certain industrial processes.

Methane (CH4): Methane is a potent greenhouse gas with a much higher heat-trapping ability per molecule compared to carbon dioxide. It is released during natural processes like wetland decomposition and as a byproduct of livestock digestion (enteric fermentation). It is also emitted from the extraction and transportation of fossil fuels and from landfills.

Nitrous Oxide (N2O): Nitrous oxide is another powerful greenhouse gas. It is released through agricultural practices (fertilizer use), industrial processes, and the combustion of fossil fuels. Nitrous oxide also contributes to ozone depletion in the stratosphere.

Fluorinated Gases: These gases include hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). They are synthetic compounds used in various industrial applications, including refrigeration, air conditioning, and electronics manufacturing. While they are present in much smaller quantities than CO2, they have high global warming potentials (GWPs) and can remain in the atmosphere for a long time.

Water Vapor: Water vapor is the most abundant greenhouse gas in the atmosphere. While it is a natural component of the Earth's climate system, its concentration increases with rising temperatures, amplifying the greenhouse effect.

21.  Bagassosis is due to inhalation of ( UPPSC PYQ)

a) Cotton dust

b) Sugarcane dust

c) Silica dust

d) Coal dust

Answer. b) Sugarcane dust;

Bagassosis is an occupational lung disease caused by the inhalation of dust from the dry processing of sugarcane, particularly bagasse. Bagasse is the fibrous residue left over after sugarcane is crushed to extract its juice, and it is commonly used as a source of renewable energy, animal feed, and the production of paper and building materials.

22. Which equipment is used for the calculation of the amount of bleaching powder needed for the purification of water? ( UPPSC PYQ)

a) Pasteur Chamberland filter

b) Berekefeld filter

c) Horrock's apparatus

d) Katadyn filter

Answer. c) Horrock's apparatus;

Pasteur Chamberland Filter:

The Pasteur Chamberland filter is a type of laboratory filter used in microbiology for sterilizing or filtering liquids. It consists of a ceramic filter made of unglazed porcelain. The filter has tiny pores that can trap microorganisms and particles.

This filter was developed by French scientist Louis Pasteur and his colleague Charles Chamberland in the late 19th century. It played a significant role in advancing microbiological research and helped demonstrate the existence of microorganisms.

Berkefeld Filter:

The Berkefeld filter is a gravity-based water filter that was invented by Friedrich Berkefeld in the late 19th century. It was commonly used for household water purification and in field operations for military units.

The filter consists of a ceramic candle or cylinder with fine pores. Water is poured into the top of the filter, and gravity forces it through the ceramic, trapping impurities and microorganisms, resulting in cleaner water.

Katadyn Filter:

Katadyn is a well-known brand that manufactures portable water filtration devices for outdoor enthusiasts, campers, hikers, and emergency preparedness. 

23. The chief source of Hydrogen Sulphide pollutants is ( UPPSC PYQ)

a) Decaying vegetation and animal matter

b) Automobiles

c) Oil Refineries

d) Thermal Power Plants

Answer. a) Decaying vegetation and animal matter;

 In sewage and wastewater treatment plants, the breakdown of organic matter can produce H2S when conditions become anaerobic.

Anaerobic conditions in manure storage and livestock facilities can result in the release of hydrogen sulfide gas.

24. Consider the following:

1. Atrazine

2. Butachlor

3. Paraquat

4. Alachlor

Which of the above is/are used as weedicides?

a) only 1

b) only 1 and 2

c) only 2 and 3

d) All of the above

Answer. d) All of the above;

Weedicides, also known as herbicides, are chemicals specifically designed to control or eliminate unwanted vegetation, commonly referred to as weeds. These chemicals are used in agriculture, landscaping, and other applications to manage weed growth and improve the growth of desired plants. There are various types of herbicides, classified based on their mode of action. Some common chemical classes of herbicides include:

Glyphosate: Glyphosate is one of the most widely used herbicides globally. It works by inhibiting an enzyme involved in plant growth. Products like Roundup contain glyphosate as their active ingredient.

2,4-D (2,4-Dichlorophenoxyacetic acid): 2,4-D is a synthetic auxin that disrupts normal plant growth, leading to uncontrolled cell division and growth in weeds. It is often used in selective herbicides that target broadleaf plants while sparing grasses.

Dicamba: Dicamba is another synthetic auxin herbicide that is often used in combination with other herbicides to control broadleaf weeds in crops like soybeans and cotton.

Atrazine: Atrazine is a triazine herbicide used primarily in cornfields to control grassy and broadleaf weeds. It inhibits photosynthesis in plants.

Paraquat: Paraquat is a non-selective herbicide that acts as a contact herbicide, causing rapid desiccation and death of treated plants. It is used to control various types of weeds.

Imazapyr and Imazapic: These herbicides are used for the control of annual and perennial grasses and broadleaf weeds, often in non-crop areas like roadsides and industrial sites.

Metolachlor: Metolachlor is a pre-emergence herbicide used to control grasses and certain broadleaf weeds in crops like corn, soybeans, and cotton.

Glufosinate: Glufosinate is a non-selective herbicide that inhibits an enzyme involved in amino acid synthesis, causing plant death. It is used in various crops and genetically modified crops that are resistant to glufosinate.

25. Which one of the following pairs is not correctly matched?

a) Dry Ice: Solid Carbon Dioxide

b) Sevin: Pesticide

c) Teflon: Fluorinated Polymers

d) Fullerene: Fluorinated Organic Compounds

Answer. d) Fullerene: Fluorinated Organic Compounds;

Dry Ice (Solid Carbon Dioxide):

Dry ice is the solid form of carbon dioxide (CO2) at extremely low temperatures (about -78.5°C or -109.3°F). It is called "dry ice" because it doesn't melt into a liquid; instead, it sublimates directly from a solid to a gas.

Dry ice is commonly used for cooling and refrigeration, especially in the food industry for shipping perishable items. It is also used for creating special effects like fog in the entertainment industry and for certain laboratory applications.

Sevin (Carbaryl):

Sevin is a widely used insecticide that contains the active ingredient carbaryl. It is used to control a variety of pests in agriculture, gardens, and lawns.

Carbaryl works by interfering with the nervous system of insects, leading to their paralysis and death. It is available in various formulations, including dusts, sprays, and granules.

Teflon :

Teflon is a brand name for polytetrafluoroethylene (PTFE), a synthetic fluoropolymer known for its non-stick and high-temperature-resistant properties.

Teflon is widely used as a non-stick coating on cookware, such as frying pans. It is also used in various industrial applications, including as a lining for pipes and containers that handle corrosive chemicals. Teflon is valued for its ability to repel water and resist chemical corrosion.


Fullerene refers to a class of carbon molecules that are composed of carbon atoms arranged in a spherical, tubular, or cage-like structure.

The most famous fullerene is the buckminsterfullerene (C60), which has a soccer ball-like structure composed of 60 carbon atoms. Fullerenes have unique properties and have been studied for their potential applications in nanotechnology, drug delivery systems, and as superconductors.

26. Which of the following is an example of non-point source pollution?

a) A factory discharging chemicals into a river

b) An oil spill from a tanker

c) Runoff from agricultural field

d) A sewage treatment plant releasing treated water into a river

Answer. c) Runoff from agricultural field


You may like also:

Next Post »