Pollution - Competency-Based Question Bank (with Answers)

Section A: Case-Based Questions

Case Study 1: Lake covered with algae, fish dying, village runoff.

1. Identify the phenomenon.
   • Answer: Eutrophication (followed by Algal Bloom).
2. Nutrients responsible.
   • Answer: Nitrates and Phosphates (from detergents and fertilizers).
3. Designing: Restoration methods.
   • Answer: Diverting sewage away from the lake, and "Bioremediation" (using plants/microbes to absorb excess nutrients).
4. Analysis: Why are fish dying?
   • Answer: Algae die and are decomposed by bacteria, which use up all the dissolved Oxygen in the water, causing fish to suffocate.
5. Define "BOD".
   • Answer: Biological Oxygen Demand - the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material in a water sample.

Case Study 2: City smog in winter, eye irritation. 6. Identify the pollution.

• Answer: Smog (Smoke + Fog).

7. What is "Photochemical Smog"?
   • Answer: Smog produced when sunlight reacts with nitrogen oxides and volatile organic compounds (from car exhausts).
8. Creating: Health advisory.
   • Answer: "Wear N95 masks, avoid outdoor exercise in the morning, use air purifiers, and keep hydrated."
9. Critical Thinking: Stubble burning contribution.
   • Answer: Releases massive amounts of smoke and particulate matter (PM) which get trapped in the cold, still air of winter (Temperature Inversion).
10. PM 2.5 and PM 10 role.
    • Answer: These fine particles can penetrate deep into the lungs and even enter the bloodstream, causing asthma, bronchitis, and heart disease.

Section B: Assertion-Reasoning Questions

Directions: (a) Both A/R true, R explains A; (b) Both true, R doesn't explain A; (c) A true, R false; (d) A false, R true.

11. Assertion (A): Taj Mahal is turning yellow. Reason (R): Acid rain reacts with marble.
    • Answer: (a) Both A and R are true and R is the correct explanation.
12. Assertion (A): Ozone in stratosphere is "Good Ozone". Reason (R): Shields from UV radiation.
    • Answer: (a) Both A and R are true and R is the correct explanation.
13. Assertion (A): Plastic bags should be banned. Reason (R): They are non-biodegradable.
    • Answer: (a) Both A and R are true and R is the correct explanation.
14. Assertion (A): CO2 is a Green House Gas. Reason (R): It traps infrared radiation.
    • Answer: (a) Both A and R are true and R is the correct explanation.
15. Assertion (A): Noise pollution can cause hypertension. Reason (R): Loud noise increases adrenaline.
    • Answer: (a) Both A and R are true and R is the correct explanation.

Section C: Creating and Designing (Application & Analysis)

16. Designing: Rainwater Harvesting.
    • Answer: [Roof -> Pipes -> Filter -> Storage Tank -> Groundwater Recharge].
17. Creating: Slogan.
    • Answer: "Clean India, Green India."
18. Analysis: Biodegradable vs Non-biodegradable.
    • Answer: Biodegradable: Can be broken down by microbes (Paper, Food). Non-biodegradable: Cannot be broken down (Plastic, Glass, DDT).
19. Designing: Pollutants table.
    • Answer: [CO: Car exhaust (suffocation). SO2: Factories (acid rain). DDT: Pesticide (Biomagnification). Mercury: Industrial waste (Minamata disease)].
20. Visualisation: Greenhouse Effect.
    • Answer: [Description: Solar rays enter, but heat rays cannot escape through the layer of GHGs].
21. Application: Why ban CFCs?
    • Answer: They release chlorine atoms in the stratosphere which break down Ozone ($O_3$) molecules into Oxygen ($O_2$), thinning the ozone layer.
22. Creating: Waste-to-Wealth.
    • Answer: Making paper mache bowls or recycling into cardboard.
23. Analysis: Biomagnification of DDT.
    • Answer: DDT concentration increases at each trophic level because it is not metabolized; it leads to thin eggshells in birds of prey.
24. Designing: Reduce Noise Pollution.
    • Answer: Using silencers in machines, "No Honking" zones near hospitals, and planting trees (Green Muffler).
25. Creating: Speech on Single-Use Plastic.
    • Answer: [Focus on ocean pollution, death of cattle/turtles, and microplastics in food].

Section D: Competency & Critical Thinking

26. Acid Rain.
    • Answer: Rain containing nitric and sulfuric acids. pH below 5.6.
27. Scenario: Nuclear radiation risks.
    • Answer: DNA damage leading to genetic mutations, leukemia, and other cancers.
28. Critical Thinking: Is Greenhouse Effect entirely bad?
    • Answer: No, without it, the Earth's average temperature would be -18°C, too cold for most life. The problem is the enhanced effect.
29. Application: Scrubber/Precipitator.
    • Answer: Used in chimney stacks to remove gases (Scrubber) or dust particles (Precipitator) from industrial smoke.
30. Pollutant vs Contaminant.
    • Answer: Pollutant: Harmful substance that reduces quality of environment. Contaminant: Substance in the wrong place but not necessarily harmful yet.
31. Diagram Based: GHG pie chart.
    • Answer: CO2 accounts for approx 60% of the enhanced greenhouse effect.
32. Oil Spills impact.
    • Answer: Coats feathers of birds (hypothermia) and prevents gas exchange for marine life.
33. Analysis: Unleaded petrol.
    • Answer: Lead is a neurotoxin; removing it prevents lead poisoning and allows the use of catalytic converters in cars.
34. Competency: BS-VI norms.
    • Answer: Stringent standards for vehicle tailpipe emissions (CO, HC, NOx, and PM).
35. Case: Minamata disease.
    • Answer: Methyl Mercury poisoning.
36. Creating: Planting trees hypothesis.
    • Answer: Trees are "carbon sinks"; they absorb CO2 for photosynthesis, reducing the atmospheric concentration.
37. Designing: 3Rs visual.
    • Answer: [Reduce: Use less. Reuse: Use again. Recycle: Process into new things].
38. Application: Organic Farming.
    • Answer: Uses natural fertilizers (compost) and biopesticides, preventing the accumulation of toxic chemicals in the soil.
39. Critical Thinking: Bio-indicators (Lichens).
    • Answer: Lichens are highly sensitive to SO2; their absence in an area indicates high air pollution.
40. Analysis: Carbon Footprint.
    • Answer: The total amount of greenhouse gases produced by an individual's actions (transport, food, energy use).

Section E: Advanced Competency

41. Scenario: Odd-Even rule.
    • Answer: Reduces the number of vehicles on the road, lowering the emission of pollutants during severe smog episodes.
42. Designing: E-Waste Management poster.
    • Answer: "Don't trash your tech. Dispose of electronics at authorized collection centers."
43. Application: Montreal Protocol.
    • Answer: An international treaty signed to phase out the production of ozone-depleting substances.
44. Creating: Global Warming quiz.
    • Answer: [True: Rising sea levels will flood coastal cities. True: Glaciers are melting at record rates].
45. Case Study: Thermal Pollution.
    • Answer: Warm water holds less dissolved Oxygen, which can cause mass death of fish and disrupt breeding.
46. Sustainable Development.
    • Answer: Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
47. Critical Thinking: Electric vehicles (EVs).
    • Answer: EVs reduce tailpipe emissions, but the electricity must come from renewable sources, and battery mining/disposal must be managed.
48. Analysis: Thermal vs Hydro power.
    • Answer: Thermal: High air pollution (CO2/SO2). Hydro: No air pollution but causes habitat destruction and displacement of people.
49. Designing: Global Temp graph.
    • Answer: Shows a "hockey stick" curve with a sharp rise starting from the Industrial Revolution.
50. Creating: Ocean Cleanup device.
    • Answer: [E.g., A floating barrier with a screen that collects plastic using ocean currents].