Answer: A

Explanation:

Many factories located in surface water areas, lakes, canals and river banks discharge their waste into rivers. Many toxic chemicals are present in this waste, as a result of which they spread diseases among humans. Underground water also gets polluted by this. When these chemicals enter the human body, they cause many diseases.

When mercury dissolves in water, it is absorbed by aquatic plants and it enters herbivorous fishes. These fish are eaten by other carnivorous fish. Ultimately, after mercury enters the human body, it suppresses the chromosomes in gamete formation and brings about genetic changes. Due to this, a disease called Miniamata occurs. Symptoms of this disease are mental retardation, impaired vision and relaxation of muscles. Hence pair 1 is not correctly matched.

Lead disrupts metabolism and destroys enzymes. As a result, problems like congenital deformities, anemia, loss of appetite and formation of blue lines near the gums etc. arise. Hence, pair 2 is not correctly matched.

Cadmium accumulates in the liver and kidneys, causing hypertension and kidney damage . Hence, pair 3 is correctly matched.

Radioactive strontium- 90 reduces calcium and enters the bones and causes bone cancer. Due to the action of iodine-131, sodium and potassium are reduced, which causes genetic and other functional changes. Hence, pair 4 is not correctly matched.

Nitrates dissolved in water reach the stomach and react with hemoglobin and weaken its oxygen carrying power. Blue baby syndrome occurs due to excess nitrate in drinking water. Inorganic nitrates and phosphates greatly increase the growth of plants growing in lakes and reservoirs.

Answer: C

Explanation:

Petroleum coke or petcoke is a final carbon-rich solid obtained as a by-product from oil refining plants. It is actually the leftover sludge from oil plants. It contains high amounts of carbon, the substance responsible for global warming, and sulfur which is harmful for the heart and lungs. Hence, statement 1 is correct.

Petcoke contains 90 percent carbon and emits much more carbon dioxide (about 5-10 percent more) per unit energy than coal. It is a material with high effervescence, low cost and low maintenance cost. India is the world's largest petcoke consumer country. It is also a recognized fuel in many states – Andhra Pradesh, Telangana, Gujarat and Karnataka etc. Hence, statement 2 is correct.

Answer: A

Explanation:

The structure which is located within the earth's surface is called aquifer, in which a large amount of water is filled between soft rocks and small stones. The uppermost layer of the aquifer is called the water table. Generally clean groundwater is found only in aquifer. Hence, option (a) is correct.

Answer: C

Explanation:

The ceramic disc of the catalyst that converts carbon monoxide emitted in vehicles into carbon dioxide is layered with palladium.

Answer: A

Explanation:

Methyl isocyanate ( MIC–C₂H₃NO ) is a volatile , colorless liquid. It is used in pesticides, polyurethane foam and is used in making plastic. Apart from this, it is also used in making rubber and adhesives. It is extremely toxic to humans through acute exposure. Its liquid and vapor are poisonous if inhaled, swallowed, or in contact with eyes or skin . On December 3, 1984, the Bhopal gas tragedy occurred due to the leakage of methyl isocyanate from a pesticide plant of a multinational company Union Carbide (now Dow Chemicals) in Bhopal, the capital of Madhya Pradesh. Hence, pair 1 is not correctly matched.

Sulfur dioxide ( SO2) is an inorganic compound. It is a heavy , colourless , poisonous gas. The main cause of acid rain is sulfur dioxide emitted from coal power plants. Hence, pair 2 is not correctly matched.

Fluoride is a widespread , non-biodegradable and is a relatively persistent pollutant. Pollution is harmful for the environment and humans. Fluoride causes a disease called fluorosis. In this, teeth become stained and bones become deformed. Hence, pair 3 is not correctly matched.

Ozone depletion causes a significant reduction in temperature in the stratosphere and upper troposphere. It is the source of heat of the stratosphere. Absorption of UV radiation by ozone, hence ozone depletion reduces warming. This can lead to serious health problems like skin diseases, skin cancer, sunburn, cataracts, early aging and weak immune system. Hence, pair 4 is correctly matched.