C.

Biogas, commonly called gobar gas, is pure methane

Activated sludge is a process dealing with the treatment of sewage and industrial waste waters. Atmospheric air on pure oxygen is introduced to a mixture of primary treated or screened sewage (or industrial waster water) combined with organisms to develop a biological flock, which reduces the organic content of the sewage. Sediment is settlement tanks of sewage treatment plant is a rich source of aerobic bacteria because small amounts are used as inoculum in secondary treatment of biological treatment stage of sewage treatment.

B.

Radioactive fallout engulfed Bhopal

Bhopal gas Tragedy (Bhopal disaster) the world's worst industrial catastrophes. It occurred on the night of December 2/3, 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh. A leak of methyl isocyanate gas and other chemicals from the plant resulted in the exposure of hundreds of thousands of people. The official immediate death toll was 2,259 and the government of Madhya Pradesh has confirmed a total of 3,787 deaths related to the gas release. A government affidavit in 2006 stated the leak caused 5, 58125 injuries.

C.

IUCN = International Union for Conservation of Nature and Natural Resources

IUCN OR IUCNNR (International Union for Conservation of Nature and Natural Resources) is now known as WCU (World Conservation Union). Its headquarters are at Morges, Switzerland. It studies the threat to biodiversity in all parts of the world by gathering information about the geographical distribution, population size and population changes of various taxa. It prepares a red list or red data book.

C.

stratosphere

The stratosphere is the second major layer of earth's atmosphere, just above the troposphere and below the mesosphere. It is the layer of ozone (O₃). The ozone absorb high-energy UV-B and UV-C energy waves and breakdown into atomic Oxygen (O) and diatomic oxygen (O₂).

B.

Ocean

Eutrophication is a nutrient enrichment of water body resulting in increased growth of algae, other plants and animals. It is often seen is fresh water lakes. Actually, it is the natural ageing of a lake by biological enrichment of its water.