Pollution of Air and Water Part 2: MCQs (Q26–Q50)
🌍 Pollution of Air and Water – MCQs for Class 8 Science
Part 2: Q26–Q50
Q26. Which gas causes global warming along with CO₂?
A) Nitrogen
B) Oxygen
C) Methane
D) Argon
✅ Correct Answer: C) Methane
Explanation:
- C) ✔ Methane is a strong greenhouse gas, trapping more heat than CO₂.
- A, B, D) Do not cause significant greenhouse effect.
Q27. Which of the following is a renewable resource of energy?
A) Coal
B) Petroleum
C) Wind
D) Natural gas
✅ Correct Answer: C) Wind
Explanation:
- C) ✔ Wind energy is renewable, clean, and does not pollute air.
Q28. Which device is used in factories to reduce smoke particles?
A) Air conditioner
B) Electrostatic precipitator
C) Vacuum cleaner
D) Water filter
✅ Correct Answer: B) Electrostatic precipitator
Explanation:
- B) ✔ This device removes fine particles from industrial smoke.
Q29. Which of the following is NOT a consequence of air pollution?
A) Asthma
B) Bronchitis
C) Malaria
D) Lung cancer
✅ Correct Answer: C) Malaria
Explanation:
- C) ✔ Malaria is caused by mosquitoes, not air pollution.
Q30. The main pollutant responsible for “marble cancer” of Taj Mahal is:
A) Nitrogen oxides
B) Sulphur dioxide
C) Carbon dioxide
D) Methane
✅ Correct Answer: B) Sulphur dioxide
Explanation:
- B) ✔ SO₂ mixes with water to form sulphuric acid, damaging marble.
Q31. Which of the following is a biodegradable waste?
A) Plastic
B) Polythene bag
C) Vegetable peels
D) Glass
✅ Correct Answer: C) Vegetable peels
Explanation:
- C) ✔ Biodegradable → can be broken down naturally.
- A, B, D) Non-biodegradable, remain in environment for years.
Q32. The main source of carbon monoxide in cities is:
A) Volcanoes
B) Burning petrol and diesel
C) Soil bacteria
D) Lightning
✅ Correct Answer: B) Burning petrol and diesel
Explanation:
- B) ✔ Vehicles emit CO due to incomplete combustion.
Q33. The “Blue Baby Syndrome” is caused by excess of:
A) Oxygen in water
B) Nitrates in water
C) Sulphur dioxide in air
D) Lead in water
✅ Correct Answer: B) Nitrates in water
Explanation:
- B) ✔ Excess nitrates lower oxygen in infants’ blood, causing blue skin.
Q34. The greenhouse effect leads to:
A) Global cooling
B) Global warming
C) Acid rain
D) Ozone layer formation
✅ Correct Answer: B) Global warming
Explanation:
- B) ✔ Heat-trapping gases raise Earth’s temperature.
Q35. Which of these is NOT a method of water purification at home?
A) Boiling
B) Filtration
C) Sedimentation
D) Burning
✅ Correct Answer: D) Burning
Explanation:
- D) ✔ Burning cannot purify water.
- A, B, C) Common household purification methods.
Q36. Excessive use of fertilizers and pesticides causes:
A) Increase in biodiversity
B) Soil and water pollution
C) Ozone depletion only
D) Noise pollution
✅ Correct Answer: B) Soil and water pollution
Explanation:
- B) ✔ Chemicals seep into soil and water, harming life.
Q37. Which of these is a natural air purifier?
A) Factories
B) Automobiles
C) Plants
D) Air conditioners
✅ Correct Answer: C) Plants
Explanation:
- C) ✔ Plants absorb CO₂ and release oxygen, cleaning the air.
Q38. Which pollutant is responsible for respiratory diseases?
A) Dust and smoke
B) Oxygen
C) Nitrogen
D) Argon
✅ Correct Answer: A) Dust and smoke
Explanation:
- A) ✔ Dust, smoke, and particulates cause asthma, bronchitis.
Q39. Which of the following causes noise pollution?
A) Tree plantation
B) Honking of vehicles
C) Photosynthesis
D) Rainfall
✅ Correct Answer: B) Honking of vehicles
Explanation:
- B) ✔ Vehicle horns add to noise pollution in cities.
Q40. Which of these is a non-biodegradable waste?
A) Banana peel
B) Paper
C) Polythene
D) Cotton cloth
✅ Correct Answer: C) Polythene
Explanation:
- C) ✔ Polythene persists for years, harming soil and water.
Q41. Which gas is known as “Laughing Gas”?
A) Carbon dioxide
B) Nitrous oxide
C) Methane
D) Carbon monoxide
✅ Correct Answer: B) Nitrous oxide
Explanation:
- B) ✔ N₂O contributes to greenhouse effect and ozone depletion.
Q42. Which practice can reduce water pollution in villages?
A) Using open drains
B) Dumping sewage in ponds
C) Building septic tanks
D) Throwing waste into rivers
✅ Correct Answer: C) Building septic tanks
Explanation:
- C) ✔ Septic tanks treat human waste safely.
Q43. Which pollutant causes Minamata disease?
A) Mercury
B) Lead
C) Arsenic
D) Cadmium
✅ Correct Answer: A) Mercury
Explanation:
- A) ✔ Mercury-contaminated water in Japan caused Minamata disease.
Q44. Which of these is an effect of noise pollution?
A) Hearing loss
B) Increased crop yield
C) Stronger immune system
D) Better sleep
✅ Correct Answer: A) Hearing loss
Explanation:
- A) ✔ Continuous loud noise damages hearing and causes stress.
Q45. Which of these gases is responsible for photochemical smog?
A) Oxygen
B) Nitrogen dioxide
C) Helium
D) Hydrogen
✅ Correct Answer: B) Nitrogen dioxide
Explanation:
- B) ✔ NO₂ reacts with sunlight and hydrocarbons to form smog.
Q46. Ganga Action Plan was launched to control:
A) Air pollution
B) Noise pollution
C) Water pollution
D) Soil erosion
✅ Correct Answer: C) Water pollution
Explanation:
- C) ✔ GAP aimed to clean the Ganga River by reducing waste inflow.
Q47. The primary cause of ozone layer depletion is:
A) Excess CO₂
B) CFCs
C) Smoke
D) NO₂
✅ Correct Answer: B) CFCs
Explanation:
- B) ✔ Chlorofluorocarbons break down ozone molecules in stratosphere.
Q48. Which international agreement was signed to reduce ozone depletion?
A) Paris Agreement
B) Kyoto Protocol
C) Montreal Protocol
D) Geneva Convention
✅ Correct Answer: C) Montreal Protocol
Explanation:
- C) ✔ Signed in 1987 to phase out CFCs and ozone-depleting substances.
Q49. Water pollution affects aquatic life by reducing:
A) Oxygen level
B) Temperature
C) Carbon dioxide
D) Nitrogen
✅ Correct Answer: A) Oxygen level
Explanation:
- A) ✔ Pollutants deplete dissolved oxygen, suffocating aquatic animals.
Q50. Which of the following is NOT a greenhouse gas?
A) Methane
B) Nitrous oxide
C) Carbon dioxide
D) Oxygen
✅ Correct Answer: D) Oxygen
Explanation:
- D) ✔ Oxygen is essential for breathing but does not trap heat.
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