🌍 Environmental Issues – MCQs

Part 1: Q1–Q25

Q1. The major cause of ozone depletion is emission of:

a) CO₂
b) CFCs (chlorofluorocarbons) ✅
c) SO₂
d) NO₂

Explanation: CFCs release chlorine radicals in the stratosphere that catalyze the breakdown of ozone (O₃).

Q2. The protocol to control ozone-depleting substances is:

a) Kyoto Protocol
b) Paris Agreement
c) Montreal Protocol ✅
d) Ramsar Convention

Explanation: The 1987 Montreal Protocol targets phase-out of CFCs and other ODS.

Q3. Which gas has the highest global warming potential (GWP) among these?

a) CO₂
b) CH₄
c) N₂O
d) SF₆ ✅

Explanation: Sulphur hexafluoride (SF₆) has extremely high GWP compared to CO₂, CH₄, and N₂O.

Q4. Photochemical smog is mainly formed by the reaction of:

a) SO₂ and smoke
b) NOx and hydrocarbons in sunlight ✅
c) CO₂ and water vapor
d) O₃ and CO

Explanation: In strong sunlight, NOx + VOCs form ozone, PAN, and aldehydes → photochemical smog.

Q5. “Classical smog” (London smog) is dominated by:

a) Ozone and PAN
b) SO₂ and particulates ✅
c) NOx and ozone
d) CO and CO₂

Explanation: Sulphurous smog occurs in cold, humid conditions with high SO₂ and smoke.

Q6. Eutrophication in lakes is due to excess of:

a) Heavy metals
b) Nutrients like nitrates and phosphates ✅
c) Salts
d) Pathogens

Explanation: Nutrient enrichment causes algal blooms, decreasing oxygen and harming aquatic life.

Q7. The disease “Minamata” is associated with poisoning by:

a) Lead
b) Cadmium
c) Mercury ✅
d) Arsenic

Explanation: Mercury contamination in Minamata Bay (Japan) caused severe neurological disorders.

Q8. “Itai-itai” disease is caused by:

a) Mercury
b) Cadmium ✅
c) Arsenic
d) Lead

Explanation: Cadmium contamination led to bone pain and fractures in Japan.

Q9. Blue baby syndrome (methemoglobinemia) is due to high levels of:

a) Chlorides
b) Nitrates in drinking water ✅
c) Fluorides
d) Sulphates

Explanation: Nitrate converts hemoglobin to methemoglobin, reducing oxygen transport in infants.

Q10. The best indicator of water pollution by organic matter is:

a) pH
b) BOD ✅
c) TDS
d) Turbidity

Explanation: Biochemical Oxygen Demand (BOD) measures oxygen needed by microbes to decompose organics.

Q11. Biomagnification is most significant for:

a) Phosphates
b) DDT ✅
c) Nitrates
d) Chlorides

Explanation: Lipophilic, persistent pollutants like DDT increase in concentration along food chains.

Q12. The primary pollutant among the following is:

a) Ozone (ground-level)
b) PAN
c) NO₂ ✅
d) Formaldehyde

Explanation: NO₂ is emitted directly (primary). Ozone and PAN are secondary pollutants formed in air.

Q13. The major greenhouse gas responsible for the highest radiative forcing is:

a) CO₂ ✅
b) CH₄
c) N₂O
d) CFC-12

Explanation: Due to its abundance and long lifetime, CO₂ contributes the most to warming overall.

Q14. Algal bloom often results in:

a) Increased dissolved oxygen
b) Fish kills due to oxygen depletion ✅
c) Reduction in BOD
d) Increased water transparency

Explanation: Decomposition of excess algae consumes oxygen, causing hypoxia and fish mortality.

Q15. Bhopal gas tragedy (1984) was due to leakage of:

a) Chlorine
b) MIC (methyl isocyanate) ✅
c) Phosgene
d) Ammonia

Explanation: MIC leakage from Union Carbide plant caused thousands of deaths and injuries.

Q16. Which particulate size penetrates deepest into lungs and is most harmful?

a) PM₁₀
b) PM₂.₅ ✅
c) PM₁₀–₂.₅
d) PM₅₀

Explanation: PM₂.₅ reaches alveoli, causing cardiovascular and respiratory diseases.

Q17. Acid rain is mainly due to:

a) CO₂ and CH₄
b) SO₂ and NOx ✅
c) O₃ and CO
d) NH₃ and H₂S

Explanation: Sulfuric and nitric acids form from SO₂ and NOx, lowering rainwater pH.

Q18. The Air (Prevention and Control of Pollution) Act in India was enacted in:

a) 1972
b) 1974
c) 1981 ✅
d) 1986

Explanation: Air Act, 1981 aims to prevent and control air pollution; Water Act is 1974 and EPA is 1986.

Q19. Fly ash is a major pollutant from:

a) Cement plants
b) Thermal power plants (coal) ✅
c) Fertilizer units
d) Oil refineries

Explanation: Coal combustion generates fly ash containing silica, alumina, trace metals.

Q20. A device used to control particulate emissions from industries is:

a) Catalytic converter
b) Electrostatic precipitator ✅
c) Scrubber (only for gases)
d) Afterburner

Explanation: ESPs charge particles and collect them on plates, efficiently removing particulates.

Q21. Which of the following is NOT a biodegradable pollutant?

a) Sewage
b) Vegetable waste
c) DDT ✅
d) Paper

Explanation: DDT is persistent and resists microbial degradation.

Q22. The most effective step in solid waste management hierarchy is:

a) Landfilling
b) Recycling
c) Source reduction (reduce) ✅
d) Incineration

Explanation: Reduce > Reuse > Recycle precedes disposal for sustainability.

Q23. Excess fluoride in drinking water causes:

a) Skeletal fluorosis ✅
b) Goitre
c) Rickets
d) Anaemia

Explanation: High fluoride leads to mottled teeth and skeletal fluorosis.

Q24. Noise becomes hazardous to human health typically above:

a) 30 dB
b) 60 dB
c) 85 dB ✅
d) 100 dB

Explanation: Prolonged exposure ≥85 dB can cause hearing loss and stress.

Q25. “Greenhouse effect” is due to the trapping of:

a) Incoming shortwave radiation
b) Outgoing longwave infrared radiation ✅
c) Ultraviolet radiation
d) Cosmic radiation

Explanation: GHGs absorb terrestrial IR (longwave) and re-radiate it, warming the lower atmosphere.

🌍 Environmental Issues – MCQs

Part 2: Q26–Q50

Q26. The greenhouse gas with both natural and anthropogenic sources is:

a) Ozone
b) CO₂ ✅
c) CFCs
d) PAN

Explanation: CO₂ is released naturally (respiration, volcanoes) and by humans (burning fossil fuels, deforestation).

Q27. The greenhouse gas released from paddy fields is:

a) Nitrous oxide
b) Methane ✅
c) Ozone
d) Carbon monoxide

Explanation: Anaerobic decomposition in waterlogged rice paddies produces CH₄ (methane).

Q28. Which of the following is not a consequence of global warming?

a) Rise in sea level
b) Coral bleaching
c) Increased crop yield globally ✅
d) Extreme weather events

Explanation: Warming generally reduces productivity due to stress, pests, and irregular rainfall; not a global increase.

Q29. Which international treaty aims to reduce greenhouse gas emissions?

a) Ramsar Convention
b) Kyoto Protocol ✅
c) Montreal Protocol
d) CITES

Explanation: The Kyoto Protocol (1997) targeted legally binding reduction of greenhouse gases.

Q30. Chipko Movement was started for:

a) Air pollution control
b) Water conservation
c) Forest conservation ✅
d) Wildlife protection

Explanation: The Chipko Movement (1970s, Garhwal Himalayas) was a non-violent protest to protect forests.

Q31. The main pollutant emitted from automobiles is:

a) CO ✅
b) SO₂
c) O₃
d) Lead

Explanation: Incomplete combustion of fuel in vehicles produces carbon monoxide (CO).

Q32. Which of the following gases causes acid rain?

a) CO₂
b) SO₂ ✅
c) CH₄
d) H₂

Explanation: SO₂ + H₂O → H₂SO₄, which contributes to acid rain. NOx also plays a role.

Q33. The percentage of forest cover recommended for India is:

a) 22%
b) 25%
c) 33% ✅
d) 50%

Explanation: National Forest Policy suggests 33% forest cover for ecological balance.

Q34. The Taj Mahal in Agra is being damaged due to:

a) Ozone depletion
b) Acid rain (SO₂ emissions) ✅
c) Photochemical smog
d) Dust storms

Explanation: SO₂ emissions from industries in Mathura refinery cause acid rain → marble corrosion (marble cancer).

Q35. Which of the following is the major source of marine pollution?

a) Oil spills ✅
b) Sewage
c) Plastic waste
d) Pesticides

Explanation: While plastics and sewage matter, oil spills are the major single cause of marine pollution.

Q36. The main pollutant of Ganga River is:

a) Thermal effluents
b) Organic waste/sewage ✅
c) Heavy metals
d) Oil

Explanation: Untreated sewage and organic waste are the major pollutants of Ganga.

Q37. Which of the following is the cleanest source of energy?

a) Coal
b) Petroleum
c) Natural gas
d) Solar energy ✅

Explanation: Solar energy is renewable and does not emit greenhouse gases.

Q38. “Silent Spring,” a book highlighting pesticide pollution, was written by:

a) E.O. Wilson
b) Rachel Carson ✅
c) Charles Darwin
d) Norman Myers

Explanation: Rachel Carson (1962) warned against excessive pesticide use (especially DDT).

Q39. Deforestation leads to:

a) Global warming
b) Loss of biodiversity
c) Desertification
d) All of the above ✅

Explanation: Cutting forests contributes to warming, habitat loss, and desertification.

Q40. Which layer of atmosphere is most affected by ozone depletion?

a) Troposphere
b) Stratosphere ✅
c) Mesosphere
d) Thermosphere

Explanation: The ozone layer is in the stratosphere (10–50 km), protecting against UV radiation.

Q41. The major source of indoor air pollution in rural India is:

a) Cigarette smoke
b) Burning of biomass fuels ✅
c) Incense sticks
d) Industrial fumes

Explanation: Cow dung, firewood, crop residues → incomplete combustion → CO, particulate matter.

Q42. Which of the following is a secondary pollutant?

a) CO
b) SO₂
c) PAN (Peroxyacyl nitrate) ✅
d) NO

Explanation: PAN is formed by photochemical reactions of NOx and hydrocarbons → secondary pollutant.

Q43. Which of the following is a biodegradable pollutant?

a) Sewage ✅
b) DDT
c) Plastics
d) Heavy metals

Explanation: Sewage and organic waste are degraded by microbes, unlike persistent pollutants.

Q44. Which UN conference popularized the concept of “sustainable development”?

a) Rio Earth Summit, 1992 ✅
b) Stockholm Conference, 1972
c) Kyoto Protocol, 1997
d) Paris Agreement, 2015

Explanation: Rio Summit (1992) adopted Agenda 21 → sustainable development concept.

Q45. Which gas is produced in large amounts in sanitary landfills?

a) Oxygen
b) Methane ✅
c) Hydrogen
d) Nitrous oxide

Explanation: Anaerobic decomposition of organic matter in landfills releases methane.

Q46. Which of the following is not a greenhouse gas?

a) CO₂
b) CH₄
c) O₂ ✅
d) N₂O

Explanation: Oxygen (O₂) does not absorb infrared radiation, hence not a GHG.

Q47. Which of the following organisms are most sensitive to air pollution and are used as bioindicators?

a) Ferns
b) Mosses
c) Lichens ✅
d) Fungi

Explanation: Lichens cannot tolerate SO₂ → used as indicators of air quality.

Q48. Which of the following causes algal bloom in water bodies?

a) Heavy metals
b) Pesticides
c) Fertilizer runoff ✅
d) Plastics

Explanation: Runoff rich in phosphates and nitrates from fertilizers → eutrophication and algal bloom.

Q49. Which pollutant causes black foot disease in humans?

a) Fluoride
b) Arsenic ✅
c) Lead
d) Cadmium

Explanation: Arsenic-contaminated water leads to black foot disease (skin lesions, gangrene).

Q50. Which Indian Act is specifically aimed at handling hazardous chemicals?

a) Wildlife Protection Act, 1972
b) Air Act, 1981
c) Environment Protection Act, 1986 ✅
d) Forest Conservation Act, 1980

Explanation: Environment Protection Act (1986) empowers the government to regulate hazardous chemicals.

🌍 Environmental Issues – MCQs

Part 3: Q51–Q75

Q51. The main pollutant of photochemical smog is:

a) SO₂
b) Ozone ✅
c) CO
d) Ammonia

Explanation: Photochemical smog contains ozone, PAN, aldehydes, formed when NOx and hydrocarbons react in sunlight.

Q52. Which pollutant is responsible for “bronchitis” in humans?

a) Ozone
b) SO₂ ✅
c) CO₂
d) CO

Explanation: SO₂ is an irritant gas that damages the respiratory tract and causes bronchitis.

Q53. Which heavy metal causes neurological damage and learning disabilities in children?

a) Lead ✅
b) Arsenic
c) Cadmium
d) Chromium

Explanation: Lead poisoning affects the nervous system, particularly in children.

Q54. Which air pollutant causes the most deaths globally?

a) Ozone
b) PM₂.₅ ✅
c) SO₂
d) CO

Explanation: PM₂.₅ penetrates deep into lungs and bloodstream, causing cardiovascular and respiratory deaths.

Q55. Greenhouse effect leads to:

a) Depletion of ozone
b) Increase in Earth’s average temperature ✅
c) Acid rain
d) Smog

Explanation: Trapping of longwave infrared radiation by GHGs → global warming.

Q56. The major source of carbon monoxide in cities is:

a) Power plants
b) Vehicles ✅
c) Forest fires
d) Volcanoes

Explanation: Incomplete combustion of petrol/diesel in automobiles releases CO.

Q57. Which river is the focus of the “Namami Gange Programme”?

a) Yamuna
b) Ganga ✅
c) Narmada
d) Godavari

Explanation: The Namami Gange Mission aims to clean and rejuvenate River Ganga.

Q58. Which of the following is a natural air pollutant?

a) Dust storm ✅
b) Industrial smoke
c) Vehicular exhaust
d) Power plant emissions

Explanation: Dust storms, volcanoes, and pollen are natural pollutants.

Q59. The greenhouse gas emitted in the largest quantity by human activities is:

a) Methane
b) CO₂ ✅
c) Nitrous oxide
d) CFCs

Explanation: Burning of fossil fuels makes CO₂ the dominant anthropogenic GHG.

Q60. What does “CFC” stand for?

a) Chlorine Fluoride Compound
b) Chlorofluorocarbon ✅
c) Carbon Fluoride Compound
d) Chloroform Compound

Explanation: Chlorofluorocarbons are synthetic chemicals used in refrigeration, aerosols, foams.

Q61. Which city is most famous for photochemical smog?

a) Delhi
b) Los Angeles ✅
c) Beijing
d) Tokyo

Explanation: Los Angeles (USA) is a classic example due to traffic, industry, and sunlight.

Q62. E-waste refers to:

a) Industrial waste
b) Plastic waste
c) Electronic waste ✅
d) Agricultural waste

Explanation: E-waste = discarded electronic products (computers, mobiles, TVs) containing toxic metals.

Q63. Which international agreement controls transboundary movement of hazardous waste?

a) Kyoto Protocol
b) Basel Convention ✅
c) Montreal Protocol
d) Stockholm Convention

Explanation: Basel Convention (1989) prevents dumping of hazardous wastes in developing countries.

Q64. Which of the following is NOT a persistent pollutant?

a) Plastics
b) DDT
c) Sewage ✅
d) Heavy metals

Explanation: Sewage is biodegradable; others are persistent and accumulate.

Q65. Which is the major source of NOx in the atmosphere?

a) Automobiles ✅
b) Volcanoes
c) Agriculture
d) Cement factories

Explanation: Automobile exhaust is the largest source of NO and NO₂ emissions.

Q66. Which of the following is the least polluting fuel for vehicles?

a) Petrol
b) Diesel
c) LPG ✅
d) Coal gas

Explanation: LPG (Liquefied Petroleum Gas) burns cleanly, producing very little SO₂, CO, or particulates.

Q67. Which of the following countries is the largest emitter of CO₂?

a) USA
b) India
c) China ✅
d) Russia

Explanation: China emits the most CO₂ due to heavy industrialization and coal use.

Q68. The main cause of desertification is:

a) Overgrazing ✅
b) Floods
c) Earthquakes
d) Volcanic eruptions

Explanation: Overgrazing, deforestation, and poor irrigation degrade soil → desertification.

Q69. Which type of UV radiation is most harmful but blocked by ozone?

a) UV-A
b) UV-B
c) UV-C ✅
d) Infrared

Explanation: UV-C (100–280 nm) is most harmful but absorbed completely by ozone & O₂ in stratosphere.

Q70. Which gas causes respiratory problems and acid rain?

a) CH₄
b) SO₂ ✅
c) N₂
d) CO₂

Explanation: SO₂ irritates lungs and forms H₂SO₄ → acid rain.

Q71. Which country hosted the first global environment conference in 1972?

a) USA
b) India
c) Sweden (Stockholm) ✅
d) Brazil

Explanation: Stockholm Conference, 1972 (Sweden) → first UN conference on environment.

Q72. Which heavy metal is used in rechargeable batteries and causes water pollution?

a) Mercury
b) Cadmium ✅
c) Arsenic
d) Chromium

Explanation: Cadmium from Ni-Cd batteries contaminates soil and water.

Q73. A catalytic converter in automobiles helps in reducing:

a) CO, hydrocarbons, and NOx ✅
b) O₃ and PAN
c) SO₂ and CO₂
d) Dust and smoke

Explanation: Catalytic converters oxidize CO and hydrocarbons → CO₂ & H₂O; reduce NOx → N₂.

Q74. The most abundant greenhouse gas in the atmosphere is:

a) CO₂
b) CH₄
c) Water vapour ✅
d) O₃

Explanation: Water vapour is the most abundant natural GHG, but human activities mainly add CO₂.

Q75. The international treaty to reduce persistent organic pollutants (POPs) is:

a) Montreal Protocol
b) Stockholm Convention ✅
c) Basel Convention
d) Kyoto Protocol

Explanation: Stockholm Convention (2001) controls POPs like DDT, PCBs, dioxins.

🌍 Environmental Issues – MCQs

Part 4: Q76–Q100

Q76. Which of the following is a biodegradable waste?

a) Plastic
b) Sewage ✅
c) DDT
d) Glass

Explanation: Sewage and organic waste can be decomposed by microbes, unlike plastics and DDT.

Q77. Which of the following is NOT a greenhouse gas?

a) CO₂
b) CH₄
c) O₂ ✅
d) N₂O

Explanation: Oxygen (O₂) does not absorb infrared radiation, so it is not a GHG.

Q78. The pH of acid rain is usually:

a) 7
b) >7
c) <5.6 ✅
d) 10

Explanation: Rainwater below pH 5.6 is considered acid rain due to SO₂ and NOx.

Q79. Which of the following is an example of solid waste management?

a) Catalytic converter
b) Landfilling ✅
c) Scrubber
d) ESP

Explanation: Landfilling is a common method of managing solid municipal waste.

Q80. Which gas is released in large amounts from coal mining?

a) CO
b) CH₄ ✅
c) SO₂
d) O₃

Explanation: Methane (CH₄) is trapped in coal seams and released during mining.

Q81. The major pollutant from thermal power plants is:

a) CO₂ ✅
b) NO₂
c) O₃
d) CFCs

Explanation: CO₂ is released in large amounts from burning coal in thermal plants.

Q82. Which of the following contributes to ozone hole formation?

a) CO₂
b) CFCs ✅
c) SO₂
d) N₂

Explanation: CFCs release chlorine radicals that destroy stratospheric ozone.

Q83. The first Earth Day was celebrated in:

a) 1968
b) 1970 ✅
c) 1972
d) 1985

Explanation: 22nd April 1970 was celebrated as the first Earth Day.

Q84. BOD level is high in:

a) Clean water
b) Polluted water ✅
c) Distilled water
d) Rainwater

Explanation: Higher organic matter → higher BOD, indicating pollution.

Q85. Which of the following is NOT an effect of noise pollution?

a) Hypertension
b) Hearing loss
c) Sleep disturbance
d) Anaemia ✅

Explanation: Noise causes stress, hypertension, and hearing damage, but not anaemia.

Q86. Which UN programme published the famous report “Our Common Future”?

a) WHO
b) UNEP
c) World Commission on Environment and Development (WCED) ✅
d) IUCN

Explanation: The Brundtland Commission (WCED) report (1987) introduced the concept of sustainable development.

Q87. Which metal causes “blue baby syndrome”?

a) Cadmium
b) Nitrate (not a metal, but nitrate pollution) ✅
c) Lead
d) Mercury

Explanation: Nitrate-contaminated water causes methemoglobinemia, or “blue baby syndrome.”

Q88. The main source of arsenic pollution in groundwater is:

a) Fertilizers ✅
b) Automobiles
c) Volcanoes
d) Fossil fuels

Explanation: Phosphate fertilizers and natural leaching contaminate groundwater with arsenic.

Q89. Which of the following energy sources is least polluting?

a) Coal
b) Nuclear
c) Solar ✅
d) Diesel

Explanation: Solar energy is renewable and pollution-free during use.

Q90. Which of the following is not an effect of global warming?

a) Melting glaciers
b) Rising sea levels
c) Depletion of stratospheric ozone ✅
d) Extreme weather

Explanation: Ozone depletion is caused by CFCs, not global warming.

Q91. The most effective way to reduce plastic waste is:

a) Incineration
b) Recycling
c) Reducing and reusing ✅
d) Landfilling

Explanation: Following 3R principle, reducing & reusing is best.

Q92. Which of the following pollutants is most harmful to the ozone layer?

a) Methane
b) CFCs ✅
c) CO₂
d) N₂O

Explanation: CFCs release chlorine radicals, which destroy ozone molecules.

Q93. Which of the following is NOT a renewable resource?

a) Forests
b) Wind energy
c) Solar energy
d) Petroleum ✅

Explanation: Petroleum takes millions of years to form, hence non-renewable.

Q94. The Vienna Convention (1985) is related to:

a) Global warming
b) Ozone layer protection ✅
c) Biodiversity conservation
d) Hazardous waste

Explanation: Vienna Convention is the framework for protecting the ozone layer, leading to Montreal Protocol.

Q95. Which of the following is NOT an air pollutant?

a) Dust
b) SO₂
c) CO₂
d) Argon ✅

Explanation: Argon is inert and does not harm air quality.

Q96. Eutrophication leads to:

a) Increased biodiversity
b) Fish mortality ✅
c) Decrease in BOD
d) Reduced algal growth

Explanation: Nutrient enrichment → algal bloom → oxygen depletion → fish kills.

Q97. The greenhouse gas emitted most from agriculture is:

a) CO₂
b) Methane ✅
c) Ozone
d) CFCs

Explanation: Methane is released from paddy fields, livestock, and manure.

Q98. Which of the following is not a secondary pollutant?

a) PAN
b) Ozone
c) NO₂ ✅
d) Smog

Explanation: NO₂ is a primary pollutant, while ozone, PAN, and smog are secondary.

Q99. Which of the following is the cleanest fuel?

a) Diesel
b) Coal
c) LPG ✅
d) Kerosene

Explanation: LPG (Liquefied Petroleum Gas) burns with high efficiency and minimal pollutants.

Q100. The ultimate aim of environmental protection is:

a) Industrial growth
b) Ecological balance ✅
c) Urbanization
d) Deforestation

Explanation: The goal of environmental conservation is to maintain ecological balance and sustainability.

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