Air & Water Pollution — Set 3
Environment · वायु और जल प्रदूषण · Questions 21–30 of 70
What is the recommended maximum permissible level of nitrates in drinking water according to WHO?
Correct Answer: D. 50 mg/L
Excessive nitrates in water can lead to 'Blue Baby Syndrome' in infants by affecting oxygen transport in the blood. They often enter the water supply through agricultural runoff containing synthetic fertilizers. Strict monitoring of drinking water is necessary for public safety.
Which atmospheric condition traps air pollutants near the ground, especially in winter?
Correct Answer: A. Temperature inversion
In a temperature inversion, a layer of warm air sits above a layer of cooler air near the surface. This prevents the lower air from rising and dispersing pollutants, leading to high smog levels. This phenomenon is frequently observed in valley regions and large cities during calm nights.
Which pollutant is primarily responsible for 'Black Lung Disease' in coal miners?
Correct Answer: C. Coal dust
Inhaling fine coal dust over long periods leads to inflammation and scarring of the lung tissue. This condition is also known as coal workers' pneumoconiosis. It is a major occupational health hazard in the mining industry.
Which water treatment method uses microbes to break down organic pollutants?
Correct Answer: D. Biological treatment
Biological treatment involves using aerobic or anaerobic bacteria to digest dissolved organic matter. This stage is common in secondary wastewater treatment plants. It mimics the natural self-cleaning capacity of rivers but at an accelerated rate.
Which fuel is generally considered the 'cleanest' fossil fuel in terms of air pollution?
Correct Answer: A. Natural gas
Natural gas produces significantly fewer pollutants like sulfur and mercury compared to coal or oil. When burned, it emits lower levels of nitrogen oxides and carbon dioxide. It is often used as a transition fuel toward renewable energy sources.
What is the primary pollutant released from old refrigerators and air conditioners that damages the ozone layer?
Correct Answer: C. Chlorofluorocarbons (CFCs)
CFCs are stable compounds that reach the stratosphere and release chlorine atoms upon exposure to UV light. A single chlorine atom can destroy thousands of ozone molecules. The Montreal Protocol was established globally to phase out the production of these chemicals.
Which pollution causes 'Fly Ash' to be released into the environment?
Correct Answer: D. Thermal power plants
Fly ash is the fine residue produced during the combustion of pulverized coal in power plants. It contains toxic elements like arsenic and silica that can cause respiratory issues. Modern plants use electrostatic precipitators to trap this ash before it enters the air.
Which acid is formed when Carbon dioxide dissolves in ocean water, affecting coral reefs?
Correct Answer: A. Carbonic acid
Ocean acidification occurs when CO2 reacts with seawater to form carbonic acid. This process lowers the pH of the ocean and makes it harder for marine organisms to build shells and skeletons. It is a significant threat to global marine biodiversity.
Which of the following is a non-point source of water pollution?
Correct Answer: C. Agricultural runoff
Non-point source pollution comes from broad, diffuse areas rather than a single identifiable pipe. Agricultural runoff carries fertilizers and pesticides from multiple farms into nearby rivers. This type of pollution is generally harder to control and regulate than point sources.
Which chemical is often used for the 'Disinfection' of drinking water to kill harmful bacteria?
Correct Answer: D. Chlorine
Chlorination is a widely used and effective method to eliminate pathogens from municipal water supplies. While it is beneficial, excessive chlorine can react with organic matter to form potentially harmful byproducts. Many modern systems are now using UV light or ozone for disinfection.