Environmental Chemistry MCQs – Class 11 NCERT
Environmental Chemistry MCQs – Class 11 NCERT
Course: CBSE Class 11 Chemistry – MCQs with Answers and Explanations
Section: Physical Chemistry – MCQ Titles
The following 50 Multiple Choice Questions (MCQs) are strictly based on the NCERT chapter “Environmental Chemistry”. The questions are organized section-wise to ensure complete syllabus coverage and include clear, concept-clearing explanations, making them ideal for CBSE Class 11 board exam preparation.
Section A: Introduction to Environmental Chemistry
1. Environmental chemistry deals with the study of
A. chemical reactions in laboratories
B. chemical composition of the environment and changes due to human activities
C. industrial chemistry only
D. organic reactions only
Answer: B
Explanation: Environmental chemistry focuses on chemical processes occurring in air, water, and soil.
2. The environment mainly consists of
A. lithosphere only
B. atmosphere only
C. biosphere only
D. lithosphere, hydrosphere, atmosphere, and biosphere
Answer: D
Explanation: All four spheres together form the environment.
3. Which of the following is NOT a component of the environment?
A. Air
B. Water
C. Soil
D. Petroleum
Answer: D
Explanation: Petroleum is a resource, not an environmental sphere.
Section B: Atmospheric Pollution
4. Air pollution is caused mainly by
A. natural processes only
B. human activities only
C. both natural and human activities
D. radioactive decay only
Answer: C
Explanation: Volcanic eruptions and industrial emissions both cause pollution.
5. Which gas is responsible for global warming?
A. Oxygen
B. Nitrogen
C. Carbon dioxide
D. Argon
Answer: C
Explanation: CO₂ is a major greenhouse gas.
6. Greenhouse effect results in
A. cooling of earth
B. increase in earth’s temperature
C. decrease in oxygen level
D. acid rain
Answer: B
Explanation: Trapped heat increases global temperature.
7. Major contributor to photochemical smog is
A. CO₂
B. SO₂
C. NO₂ and hydrocarbons
D. O₂
Answer: C
Explanation: Nitrogen oxides and hydrocarbons react in sunlight.
Section C: Oxides of Carbon, Nitrogen, and Sulphur
8. Carbon monoxide is dangerous because it
A. is corrosive
B. reacts with ozone
C. reduces oxygen-carrying capacity of blood
D. causes acid rain
Answer: C
Explanation: CO binds with haemoglobin forming carboxyhaemoglobin.
9. Which oxide of nitrogen causes brown fumes in air?
A. NO
B. N₂O
C. NO₂
D. N₂O₅
Answer: C
Explanation: NO₂ is a brown coloured gas.
10. Sulphur dioxide mainly causes
A. ozone depletion
B. acid rain
C. photochemical smog
D. global warming
Answer: B
Explanation: SO₂ forms sulphuric acid in atmosphere.
11. Acid rain mainly contains
A. H₂CO₃
B. H₂SO₄ and HNO₃
C. HCl
D. H₃PO₄
Answer: B
Explanation: Formed from SO₂ and NO₂ reactions with water.
Section D: Water Pollution
12. The major cause of water pollution is
A. rainfall
B. industrial effluents
C. evaporation
D. condensation
Answer: B
Explanation: Untreated industrial wastes pollute water bodies.
13. Eutrophication is caused due to excess of
A. heavy metals
B. detergents and fertilisers
C. pesticides
D. hydrocarbons
Answer: B
Explanation: Nutrient enrichment leads to algal blooms.
14. Biochemical Oxygen Demand (BOD) measures
A. oxygen solubility
B. organic pollution level
C. acidity of water
D. hardness of water
Answer: B
Explanation: Higher BOD indicates more organic pollution.
15. Which metal causes Minamata disease?
A. Lead
B. Mercury
C. Cadmium
D. Arsenic
Answer: B
Explanation: Mercury poisoning caused Minamata disease in Japan.
Section E: Soil Pollution and Solid Waste
16. Soil pollution is mainly due to
A. excessive irrigation
B. pesticides and fertilisers
C. rainfall
D. weathering
Answer: B
Explanation: Agrochemicals accumulate in soil.
17. Non-biodegradable waste includes
A. vegetable peels
B. paper
C. plastics
D. sewage
Answer: C
Explanation: Plastics do not decompose naturally.
18. Which of the following is biodegradable?
A. Polythene
B. Glass
C. Aluminium foil
D. Food waste
Answer: D
Explanation: Organic waste decomposes naturally.
19. Solid waste management aims to
A. burn waste
B. recycle waste
C. reduce, reuse, and recycle waste
D. dump waste
Answer: C
Explanation: 3R principle minimizes pollution.
Section F: Ozone Layer and Its Depletion
20. Ozone layer is present in
A. troposphere
B. stratosphere
C. mesosphere
D. thermosphere
Answer: B
Explanation: Ozone layer absorbs harmful UV radiation.
21. Ozone depletion is mainly caused by
A. CO₂
B. SO₂
C. CFCs
D. CH₄
Answer: C
Explanation: Chlorofluorocarbons destroy ozone molecules.
22. Ozone layer protects life by absorbing
A. infrared rays
B. visible light
C. ultraviolet radiation
D. X-rays
Answer: C
Explanation: UV radiation is harmful to living organisms.
23. The ozone hole is maximum over
A. Arctic region
B. Antarctic region
C. equatorial region
D. temperate region
Answer: B
Explanation: Severe depletion occurs over Antarctica.
Section G: Green Chemistry and Pollution Control
24. Green chemistry aims to
A. increase chemical waste
B. reduce hazardous substances
C. promote industrial pollution
D. increase production cost
Answer: B
Explanation: Green chemistry focuses on eco-friendly processes.
25. Which is a principle of green chemistry?
A. maximum waste generation
B. use of toxic solvents
C. atom economy
D. high energy consumption
Answer: C
Explanation: Atom economy minimizes waste.
26. Catalysts help in pollution control by
A. increasing waste
B. lowering reaction efficiency
C. reducing energy and by-products
D. increasing emissions
Answer: C
Explanation: Catalysts improve efficiency and reduce waste.
Section H: Atmospheric Smog and Control Measures
27. Classical smog is a mixture of
A. smoke and fog
B. smoke and ozone
C. nitrogen oxides and hydrocarbons
D. sulphur dioxide and oxygen
Answer: A
Explanation: Classical smog forms in cold, humid climates.
28. Which gas is mainly responsible for acid rain?
A. CO
B. CO₂
C. SO₂
D. O₃
Answer: C
Explanation: SO₂ forms sulphuric acid in atmosphere.
29. Which device is used to control particulate pollution?
A. Catalytic converter
B. Electrostatic precipitator
C. Absorber
D. Scrubber only
Answer: B
Explanation: It removes particulate matter from exhaust gases.
30. Catalytic converters are used in automobiles to reduce
A. fuel consumption
B. noise pollution
C. exhaust emissions
D. heat loss
Answer: C
Explanation: They convert harmful gases to less harmful ones.
Section I: Global Environmental Issues
31. Global warming leads to
A. decrease in sea level
B. melting of glaciers
C. decrease in rainfall
D. ozone formation
Answer: B
Explanation: Rising temperature melts polar ice.
32. Kyoto Protocol is related to
A. ozone depletion
B. water pollution
C. greenhouse gas emission control
D. nuclear waste
Answer: C
Explanation: It aims to reduce greenhouse gas emissions.
33. Which gas has the highest global warming potential?
A. CO₂
B. CH₄
C. N₂O
D. CFCs
Answer: D
Explanation: CFCs trap much more heat than CO₂.
Section J: Conceptual NCERT-Based MCQs
34. Environmental pollution is best controlled by
A. treating pollutants after release
B. preventing pollution at source
C. diluting pollutants
D. ignoring waste
Answer: B
Explanation: Prevention is better than cure.
35. Which of the following is a secondary air pollutant?
A. CO
B. SO₂
C. NO₂
D. Ozone
Answer: D
Explanation: Ozone forms by reactions in atmosphere.
36. Acid rain affects
A. aquatic life
B. soil fertility
C. monuments
D. all of these
Answer: D
Explanation: Acid rain damages ecosystems and structures.
37. The main cause of water-borne diseases is
A. hard water
B. contaminated water
C. distilled water
D. mineral water
Answer: B
Explanation: Pathogens in polluted water cause diseases.
38. Which pollutant causes blue baby syndrome?
A. Mercury
B. Lead
C. Nitrates
D. Arsenic
Answer: C
Explanation: Excess nitrates reduce oxygen supply in infants.
Section K: Application and Analytical MCQs
39. Which method is most eco-friendly for waste disposal?
A. Landfilling
B. Incineration
C. Recycling
D. Open dumping
Answer: C
Explanation: Recycling conserves resources and reduces waste.
40. The major source of marine pollution is
A. oil spills
B. industrial waste
C. sewage discharge
D. radioactive waste
Answer: C
Explanation: Sewage contributes significantly to marine pollution.
41. Which chemical is responsible for depletion of ozone?
A. NH₃
B. CH₄
C. CCl₂F₂
D. CO
Answer: C
Explanation: CFCs release chlorine radicals.
42. Smog formation is favoured by
A. high wind
B. rainfall
C. sunlight
D. snowfall
Answer: C
Explanation: Sunlight drives photochemical reactions.
Section L: Assertion-Type and High-Order MCQs
43. Environmental chemistry helps in
A. increasing pollution
B. understanding pollutant behaviour
C. industrial synthesis only
D. laboratory reactions
Answer: B
Explanation: It studies sources and effects of pollutants.
44. Which pollutant is biodegradable?
A. DDT
B. Plastic
C. Sewage
D. Heavy metals
Answer: C
Explanation: Organic matter in sewage decomposes naturally.
45. Which of the following reduces air pollution?
A. Burning fossil fuels
B. Afforestation
C. Use of pesticides
D. Deforestation
Answer: B
Explanation: Trees absorb CO₂ and pollutants.
46. Greenhouse gases trap heat because they
A. absorb visible light
B. absorb infrared radiation
C. reflect UV rays
D. increase oxygen level
Answer: B
Explanation: They prevent escape of infrared radiation.
47. Which substance is a bioaccumulative pollutant?
A. CO₂
B. SO₂
C. Mercury
D. Ozone
Answer: C
Explanation: Mercury accumulates in food chains.
48. The best solution to plastic pollution is
A. burning plastics
B. dumping plastics
C. recycling and reducing use
D. burying plastics
Answer: C
Explanation: Reduction and recycling are most effective.
49. Which pollutant affects visibility in cities?
A. CO₂
B. Particulate matter
C. Ozone
D. Nitrogen
Answer: B
Explanation: Suspended particles reduce visibility.
50. Environmental chemistry mainly helps in achieving
A. industrial growth
B. sustainable development
C. chemical synthesis
D. economic inflation
Answer: B
Explanation: It promotes development without harming environment.
✅ Completion Note
This completes a fully NCERT-aligned, CBSE-standard set of 50 MCQs on Environmental Chemistry, ideal for concept clarity, revision, and board exam preparation.