41. Which of the following pollutants is most harmful to aquatic life due to its ability to reduce oxygen levels in water?
A) Pesticides
B) Nitrates
C) Oil
D) Plastics
Answer: B) Nitrates
Explanation:
Nitrates contribute to eutrophication, which leads to algal blooms in water bodies. When the algae die and decompose, the process consumes large amounts of oxygen, resulting in hypoxic (low-oxygen) conditions that can be fatal to fish and other aquatic organisms.
42. Which of the following methods is most effective for the removal of suspended particles from drinking water?
A) Chlorination
B) Filtration
C) Sedimentation
D) Aeration
Answer: B) Filtration
Explanation:
Filtration is the most effective method for removing suspended particles from drinking water. It involves passing the water through a filter medium that traps particles and contaminants, ensuring cleaner and safer water for consumption.
43. Which of the following is a major source of microplastic pollution in oceans?
A) Oil spills
B) Agricultural runoff
C) Degraded plastic waste
D) Volcanic eruptions
Answer: C) Degraded plastic waste
Explanation:
Microplastic pollution in oceans is primarily caused by the breakdown of larger plastic waste into tiny particles. These microplastics persist in the environment, harm marine life, and can enter the food chain, posing health risks to humans.
44. Which of the following pollutants is most commonly responsible for the phenomenon of global warming?
A) Ozone
B) Methane
C) Chlorine
D) Nitrogen
Answer: B) Methane
Explanation:
Methane (CH₄) is one of the most potent greenhouse gases, contributing significantly to global warming. Although it is less abundant than carbon dioxide, it has a much higher global warming potential.
45. Which of the following is a common indicator of water pollution?
A) High oxygen levels
B) Low turbidity
C) High biological oxygen demand (BOD)
D) Low nitrate levels
Answer: C) High biological oxygen demand (BOD)
Explanation:
Biological Oxygen Demand (BOD) measures the amount of dissolved oxygen needed by aerobic organisms to break down organic material in water. A high BOD indicates a large amount of organic pollution, leading to low oxygen levels and poor water quality.
46. Which of the following is a common by-product of agricultural practices that leads to water pollution?
A) Heavy metals
B) Nitrates and phosphates
C) Radioactive waste
D) Dioxins
Answer: B) Nitrates and phosphates
Explanation:
Agricultural practices often involve the use of fertilizers containing nitrates and phosphates. These nutrients can run off into nearby water bodies, causing eutrophication, which leads to oxygen depletion and harmful algal blooms.
47. Which method is used to treat the oil-contaminated water in oceans?
A) Electrostatic precipitation
B) Bioremediation
C) Carbon sequestration
D) Anaerobic digestion
Answer: B) Bioremediation
Explanation:
Bioremediation uses microorganisms to break down and degrade oil pollutants in water. This method is widely employed in treating oil spills in oceans, where naturally occurring or introduced bacteria consume and neutralize the harmful components.
48. Which of the following is an effective method to control noise pollution?
A) Using taller buildings
B) Increasing urbanization
C) Installing sound barriers
D) Planting more crops
Answer: C) Installing sound barriers
Explanation:
Sound barriers, such as walls or fences, are often used to block or deflect noise from sources like highways, railways, or industrial areas. This method is effective in reducing noise pollution in residential areas.
49. Which of the following is considered a secondary air pollutant?
A) Carbon monoxide
B) Sulfur dioxide
C) Ozone
D) Methane
Answer: C) Ozone
Explanation:
Ozone (O₃) is a secondary air pollutant formed by the reaction of primary pollutants, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs), in the presence of sunlight. Ozone at ground level is harmful to human health and contributes to smog.
50. Which of the following industries is a major source of fluoride pollution?
A) Steel industry
B) Glass industry
C) Fertilizer industry
D) Textile industry
Answer: C) Fertilizer industry
Explanation:
The fertilizer industry, particularly those producing phosphate fertilizers, is a major source of fluoride pollution. Excessive fluoride in the environment can lead to fluorosis in humans and animals, which causes bone deformities and other health issues.
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