Air & Water Pollution — Set 2

Correct Answer: C. PM 2.5

PM 2.5 refers to fine particles with a diameter of less than 2.5 micrometers. Due to their tiny size, they can bypass the nose and throat and penetrate deep into the lungs and blood. They are typically generated by vehicle exhaust and industrial emissions.

Correct Answer: D. Lichens

Lichens are sensitive to air pollutants, especially sulfur dioxide, and disappear when air quality is poor. Scientists observe the growth and health of lichens to map pollution levels in a specific area. They are often called 'nature’s pollution sensors'.

Correct Answer: A. Sedimentation

Sedimentation allows heavier particles to settle at the bottom of a tank by gravity. This is a primary treatment stage that clears the water of physical impurities. It is a critical step before biological or chemical treatment begins.

Correct Answer: C. Antarctica

The correct answer is 'Antarctica'. The ozone hole is a seasonal thinning of the ozone layer over the Antarctic continent. It is caused by chemical reactions involving chlorine and bromine from human-made compounds. Extremely cold temperatures in the polar region accelerate this destructive process.

Correct Answer: D. Methane

Methane is released by anaerobic bacteria during the decomposition of organic matter in flooded fields. It is estimated to be over 25 times more effective than carbon dioxide at trapping heat over a century. Livestock farming and landfills are other major sources of this gas.

Correct Answer: A. Ozone and Nitrogen oxides

Photochemical smog is formed when sunlight reacts with nitrogen oxides and volatile organic compounds. Ground-level ozone is a major and harmful component of this type of urban pollution. It is most commonly seen in sunny, dry cities with heavy vehicle traffic.

Correct Answer: C. Lead

Lead poisoning occurs when the metal accumulates in the body, often through old paint or contaminated pipes. It is particularly dangerous for children, affecting their cognitive and physical development. Efforts to phase out leaded gasoline have significantly reduced its presence in the air.

Correct Answer: D. Industrial cooling water

Thermal pollution occurs when power plants or factories discharge warm water into natural water bodies. The increase in temperature reduces the solubility of oxygen, affecting aquatic life. It can also disrupt the breeding patterns and metabolic rates of fish.

Correct Answer: A. Biomagnification

Biomagnification occurs when persistent chemicals like DDT or mercury are stored in the tissues of organisms. Higher-level predators consume many smaller prey, leading to a much higher toxin concentration in their bodies. This process often causes reproductive failure and health issues in top-tier animals.

Correct Answer: C. Catalytic converter

A catalytic converter converts harmful carbon monoxide and nitrogen oxides into less harmful gases. It uses precious metals like platinum and palladium as catalysts for these chemical reactions. This device is a standard requirement for meeting modern emission norms.