Pollution of Air and Water Part 3: MCQs (Q51–Q75)
🌍 Pollution of Air and Water – MCQs for Class 8 Science
Part 3: Q51–Q75
Q51. Which pollutant causes respiratory problems like asthma?
A) Sulphur dioxide
B) Oxygen
C) Nitrogen
D) Argon
✅ Correct Answer: A) Sulphur dioxide
Explanation:
- A) ✔ SO₂ irritates airways and causes asthma and bronchitis.
- B, C, D) Do not cause respiratory diseases.
Q52. Which of these is an effect of oil spills in oceans?
A) Increase in oxygen
B) Birds and fish die
C) Fertile soil formation
D) Water purification
✅ Correct Answer: B) Birds and fish die
Explanation:
- B) ✔ Oil forms a layer preventing oxygen exchange → death of aquatic life.
Q53. Which gas forms acid rain when combined with water?
A) Nitrogen
B) Oxygen
C) Sulphur dioxide
D) Helium
✅ Correct Answer: C) Sulphur dioxide
Explanation:
- C) ✔ SO₂ + water = sulphuric acid, causing acid rain.
Q54. Which disease is caused by consumption of arsenic-contaminated water?
A) Minamata disease
B) Arsenicosis
C) Fluorosis
D) Cholera
✅ Correct Answer: B) Arsenicosis
Explanation:
- B) ✔ Long-term exposure to arsenic in water causes skin and organ damage.
Q55. Which chemical is used in water treatment to kill germs?
A) Carbon dioxide
B) Chlorine
C) Oxygen
D) Nitrogen
✅ Correct Answer: B) Chlorine
Explanation:
- B) ✔ Chlorination disinfects water and kills harmful microorganisms.
Q56. Which gas causes suffocation and is called a “silent killer”?
A) Oxygen
B) Carbon monoxide
C) Carbon dioxide
D) Nitrous oxide
✅ Correct Answer: B) Carbon monoxide
Explanation:
- B) ✔ CO binds with haemoglobin, reducing oxygen transport in blood.
Q57. Which of these is NOT a consequence of global warming?
A) Melting of glaciers
B) Rise in sea level
C) Increased rainfall
D) Depletion of fossil fuels
✅ Correct Answer: D) Depletion of fossil fuels
Explanation:
- D) ✔ Fossil fuel depletion is due to overuse, not global warming.
Q58. The gas produced during burning of plastics and garbage is:
A) Dioxins
B) Oxygen
C) Nitrogen
D) Hydrogen
✅ Correct Answer: A) Dioxins
Explanation:
- A) ✔ Dioxins are highly toxic and harmful to human health.
Q59. Which of these gases causes greenhouse effect and is released by paddy fields?
A) Nitrogen
B) Methane
C) Oxygen
D) Argon
✅ Correct Answer: B) Methane
Explanation:
- B) ✔ Methane is released by anaerobic decomposition in paddy fields.
Q60. Which pollutant causes thinning of ozone layer?
A) Oxygen
B) Carbon dioxide
C) CFCs
D) Helium
✅ Correct Answer: C) CFCs
Explanation:
- C) ✔ Chlorofluorocarbons break ozone molecules in the stratosphere.
Q61. Which type of waste is produced by hospitals?
A) E-waste
B) Biomedical waste
C) Plastic waste
D) Agricultural waste
✅ Correct Answer: B) Biomedical waste
Explanation:
- B) ✔ Biomedical waste includes syringes, medicines, and infected materials.
Q62. Which of these is NOT a cause of air pollution?
A) Deforestation
B) Excessive use of fossil fuels
C) Tree plantation
D) Industrial smoke
✅ Correct Answer: C) Tree plantation
Explanation:
- C) ✔ Tree plantation reduces CO₂, hence prevents pollution.
Q63. Which process causes algal bloom in water bodies?
A) Sedimentation
B) Eutrophication
C) Filtration
D) Distillation
✅ Correct Answer: B) Eutrophication
Explanation:
- B) ✔ Excess nutrients cause algae growth, reducing oxygen in water.
Q64. The harmful ultraviolet rays increase on Earth due to:
A) Ozone layer depletion
B) Greenhouse effect
C) Global warming
D) Noise pollution
✅ Correct Answer: A) Ozone layer depletion
Explanation:
- A) ✔ Ozone absorbs UV radiation, depletion allows more UV to reach Earth.
Q65. The noise level considered safe for humans is:
A) Below 85 dB
B) 100 dB
C) 120 dB
D) Above 150 dB
✅ Correct Answer: A) Below 85 dB
Explanation:
- A) ✔ Prolonged exposure above 85 dB damages hearing.
Q66. The first Indian river action plan was launched for which river?
A) Yamuna
B) Ganga
C) Brahmaputra
D) Godavari
✅ Correct Answer: B) Ganga
Explanation:
- B) ✔ Ganga Action Plan was started in 1985 to reduce river pollution.
Q67. Which gas causes acid rain and respiratory problems?
A) Nitrous oxide
B) Sulphur dioxide
C) Methane
D) Hydrogen
✅ Correct Answer: B) Sulphur dioxide
Explanation:
- B) ✔ SO₂ causes acid rain and damages lungs.
Q68. Which of these is an eco-friendly practice?
A) Open burning of waste
B) Segregation of biodegradable waste
C) Throwing garbage into rivers
D) Using excess pesticides
✅ Correct Answer: B) Segregation of biodegradable waste
Explanation:
- B) ✔ Waste segregation helps recycling and reduces pollution.
Q69. Which pollutant is emitted by automobiles and causes smog?
A) Oxygen
B) Nitrogen oxides
C) Neon
D) Argon
✅ Correct Answer: B) Nitrogen oxides
Explanation:
- B) ✔ NOx reacts with hydrocarbons and sunlight to form smog.
Q70. Which waterborne disease is caused by Vibrio cholerae?
A) Typhoid
B) Cholera
C) Dysentery
D) Diarrhoea
✅ Correct Answer: B) Cholera
Explanation:
- B) ✔ Cholera spreads through contaminated water.
Q71. Which of these is NOT a renewable energy source?
A) Wind
B) Solar
C) Petroleum
D) Hydropower
✅ Correct Answer: C) Petroleum
Explanation:
- C) ✔ Petroleum is non-renewable and polluting.
Q72. Which pollutant is responsible for blackening of buildings in cities?
A) CO₂
B) Soot and smoke
C) Nitrogen
D) Oxygen
✅ Correct Answer: B) Soot and smoke
Explanation:
- B) ✔ Smoke particles deposit on walls, darkening them.
Q73. The gas causing “acid smog” in cold weather is:
A) Methane
B) Sulphur dioxide
C) Nitrogen
D) Oxygen
✅ Correct Answer: B) Sulphur dioxide
Explanation:
- B) ✔ SO₂ forms acid smog in winter, harmful to health.
Q74. Which international agreement controls global warming?
A) Montreal Protocol
B) Kyoto Protocol
C) Paris Agreement
D) Geneva Protocol
✅ Correct Answer: B) Kyoto Protocol
Explanation:
- B) ✔ Kyoto Protocol (1997) focuses on reducing greenhouse gases.
Q75. Which of these is the main cause of waterborne diseases?
A) Clean rivers
B) Contaminated water
C) Filtered water
D) Bottled water
✅ Correct Answer: B) Contaminated water
Explanation:
- B) ✔ Contaminated water spreads cholera, typhoid, dysentery.
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