Daily Quiz: UPSC Prelims Marathon – November 17

The index is a part of the government’s Swachh Bharat Abhiyan. The index measures eight major pollutants, namely, particulate matter (PM 10 and PM 2.5), nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide, ammonia and lead. Earlier, only particulate matter, nitrogen dioxide and sulphur dioxide were being measured.

• Saint Helena is a volcanic tropical island in the South Atlantic Ocean.
• Martin’s Island, Aldabra Islands, Marshall Islands are coral Islands.

The International Seabed Authority (ISA)

• The International Seabed Authority (ISA) is an autonomous international organization established in 1994, under the 1982 United Nations Convention on the Law of the Sea.
• The Authority has its headquarters in Kingston, Jamaica.
• It was established to regulate, organize and control all mineral-related activities in the international seabed area beyond the limits of a country’s national jurisdiction, an area underlying most of the world’s oceans.
• It governs non-living resources of seabed lying in international waters.
• There are 168 members of the International Seabed Authority. The United States has not yet ratified the Law of the Sea Convention and is not a member of the International Seabed Authority.
• India is a member of ISA

• The Southwest Indian Ridge (SWIR) is a mid-ocean ridge located along the floors of the south-west Indian Ocean and south-east Atlantic Ocean.
• The SWIR is also a divergent tectonic plate boundary which separates the African Plate to the north from the Antarctic Plate to the south.
• It is distinguished by ultra-slow spreading rates (only exceeding those of the Gakkel Ridge in the Arctic) combined with a fast lengthening of its axis between the two flanking triple junctions namely Rodrigues (20°30′S 70°00′E) in the Indian Ocean and Bouvet (54°17′S 1°5′W) in the Atlantic Ocean.

• Polymetallic nodules are Fe-Mn oxide deposits, potato shape, porous, black earthy colour with size ranging from 2 to 10 cm in diameter
• These are considered as the precipitates of hot fluids from upwelling hot magma from deep interior of the oceanic crust, discharged through mineralized paths.
• The nodules were christened ‘manganese nodules’ in view of the largest component being manganese. However, since it was discovered that they contain many more important metals (although in lower percentages) the term currently in use is ‘polymetallic nodules’.

Igneous rocks are formed when molten rock cools, forming silicate mineral crystals. Felsic minerals are light colored and less dense, and mafic minerals are dark colored and more dense. The igneous rocks are generally hard and water percolates in them not so easily.

The most important characteristics of Igneous rocks are as follows:

• They usually do not occur in distinct beds or strata like sedimentary rocks.
• Igneous rocks are generally not having any fossils
• They are generally granular and crystalline.
• They are less affected by chemical weathering as the water does not percolate in them easily.

Gneissoid, slate, schist, marble, quartzite etc. are some examples of metamorphic rocks.

• The salinity of water in the surface layer of oceans depends mainly on evaporation and precipitation.
• Wind, also influences salinity of an area by transferring water to other areas.
• The ocean currents contribute to the salinity variations.