In water treatment procedures, the purpose of coagulation and flocculation is to remove microorganisms, organic matter and suspended fine particles.

CFCs, once released into the atmosphere, accumulate in the stratosphere, where they contribute to the depletion of the ozone layer.

A major source of phosgene in the air comes from the dye manufacturing industries. Poisoning caused by phosgene depends on the amount of phosgene to which a person is exposed, the route of exposure, and the length of time that a person is exposed. Phosgene gas and liquid are irritants that can damage the skin, eyes, nose, throat, and lungs.

In the process of bioleaching, microorganisms (that produce acids) are used to solubilise desired metals.

Necrosis is the death of a plant cell or group of cells while the rest of the plant is still alive. Loss of pigmentation from the leaves is known as bleaching. Presence of SO₂ in the air can cause necrosis and bleaching of leaves in plants.

Arsines breakdown RBCs in the blood, damage kidneys and cause jaundice. Inhalation of arsines can cause liver damage as well.

The highest amount of CO₂ is evolved from the ocean bed due to large amount of aquatic life. Thus, oceans contribute maximum amount of CO₂ to the atmosphere.

Wastewater discharges by pulp and paper mills contain solids, nutrients and dissolved organic matter, such as lignin. They also contain alcohols, chelating agents and inorganic materials, like chlorates and transition metal compounds.

A is true but R is false. In an area where DDT is used extensively, the population of birds declines significantly because DDT disturbs calcium metabolism in birds which causes thinning of the egg shell and their pre-mature breaking, causing less or no birth of chicks and decline in the bird's population.

Eutrophication or hypertrophication occurs when a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of algae. This process may result in oxygen depletion of the water body. At this point, oxygen-demanding bacteria take over the ecosystem, decomposing the algae and using up dissolved oxygen in the process. These bacteria increase the biological oxygen demand (BOD) of the ecosystem.