60 Steps To Prelims: Day 46 (Date : 04-05-2019)

Correct Answer : B

Explanation

• The present composition of earth’s atmosphere is chiefly contributed by nitrogen and oxygen. There are three stages in the evolution of the present atmosphere.
• The first stage is marked by the loss of primordial atmosphere. The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. This happened not only in case of the earth, but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds. Hence, statement 1 is NOT correct and 2 is correct.
• In the second stage, the hot interior of the earth contributed to the evolution of the atmosphere. During the cooling of the earth, gases and water vapour were released from the interior solid earth. This started the evolution of the present atmosphere. The process through which the gases were outpoured from the interior is called degassing. Continuous volcanic eruptions contributed water vapour and gases to the atmosphere. As the earth cooled, the water vapour released started getting condensed. The carbon dioxide in the atmosphere got dissolved in rainwater and the temperature further decreased causing more condensation and more rains. The rainwater falling onto the surface got collected in the depressions to give rise to oceans.
• Finally, the composition of the atmosphere was modified by the living world through the process of photosynthesis. Sometime around 3,800 million years ago, life began to evolve. However, around 2,500-3,000 million years before the present, the process of photosynthesis got evolved. Life was confined to the oceans for a long time. Oceans began to have the contribution of oxygen through the process of photosynthesis. Eventually, oceans were saturated with oxygen and 2,000 million years ago, oxygen began to flood the atmosphere.

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Correct Answer : C

Explanation

• All natural earthquakes take place in the lithosphere. An instrument called ‘seismograph’ records the waves reaching the surface.
• Earthquake waves are basically of two types — body waves and surface waves. Body waves are generated due to the release of energy at the focus and move in all directions travelling through the body of the earth. Hence, the name body waves. Hence, statement 1 is correct.
• The body waves interact with the surface rocks and generate new set of waves called surface waves. These waves move along the surface. The velocity of waves changes as they travel through materials with different densities. The denser the material, the higher is the velocity.
• Their direction also changes as they reflect or refract when coming across materials with different densities.
• There are two types of body waves. They are called P and S-waves. P-waves move faster and are the first to arrive at the surface. These are also called ‘primary waves’. Hence, statement 2 is NOT correct.
• The P-waves are similar to sound waves. They travel through gaseous, liquid and solid materials.
• S-waves arrive at the surface with some time lag. These are called secondary waves. An important fact about S-waves is that they can travel only through solid materials. This characteristic of the S-waves is quite important. It has helped scientists to understand the structure of the interior of the earth.
• The surface waves are the last to report on seismograph. These waves are more destructive. They cause displacement of rocks, and hence, the collapse of structures occurs. Hence, statement 3 is correct.

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Correct Answer : D

Explanation

• The lava that is released during volcanic eruptions on cooling develops into igneous rocks. The cooling may take place either on reaching the surface or also while the lava is still in the crustal portion.
• Depending on the location of the cooling of the lava, igneous rocks are classified as volcanic rocks (cooling at the surface) and plutonic rocks (cooling in the crust). The lava that cools within the crustal portions assumes different forms. These forms are called intrusive forms.
• Batholiths is a large body of magmatic material that cools in the deeper depth of the crust develops in the form of large domes. They appear on the surface only after the denudational processes remove the overlying materials. They cover large areas, and at times, assume depth that may be several km. These are granitic bodies. Batholiths are the cooled portion of magma chambers. Hence, statement 1 is correct.
• Lacoliths are large dome-shaped intrusive bodies with a level base and connected by a pipe-like conduit from below. It resembles the surface volcanic domes of composite volcano, only these are located at deeper depths. It can be regarded as the localised source of lava that finds its way to the surface. Hence, statement 2 is correct.

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Correct Answer : A

Explanation

The mapping of the ocean floor and palaeomagnetic studies of rocks from oceanic regions revealed the following facts:

1. It was realised that all along the mid oceanic ridges, volcanic eruptions are common and they bring huge amounts of lava to the surface in this area. Hence, statement 1 is correct.
2. The rocks equidistant on either sides of the crest of mid-oceanic ridges show remarkable similarities in terms of period of formation, chemical compositions and magnetic properties. Rocks closer to the mid-oceanic ridges have normal polarity and are the youngest. The age of the rocks increases as one moves away from the crest. Hence, statement 2 is correct.
3. The ocean crust rocks are much younger than the continental rocks. The age of rocks in the oceanic crust is nowhere more than 200 million years old. Some of the continental rock formations are as old as 3,200 million years. Hence, statement 3 is NOT correct.
4. The sediments on the ocean floor are unexpectedly very thin. Scientists were expecting, if the ocean floors were as old as the continent, to have a complete sequence of sediments for a period of much longer duration. However, nowhere was the sediment column found to be older than 200 million years.
5. The deep trenches have deep-seated earthquake occurrences while in the mid oceanic ridge areas, the quake foci have shallow depths.

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Correct Answer : C

Explanation

• Astana is the capital city of Kazakhstan, straddling the Ishim River in the north of the country.
• Bishkek, the capital of Kyrgyzstan, borders Central Asia's Tian Shan range. It’s a gateway to the Kyrgyz Ala-Too mountains and Ala Archa National Park, with glaciers and wildlife trails.
• Ashgabat is the capital of Turkmenistan. It’s known for its white marble buildings and grandiose national monuments.
• Tashkent is the capital and largest city of Uzbekistan, as well as the most populated city in ex-Soviet Central Asia
• As per map given below option (c) is correct.

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Correct Answer : C

Explanation

• Tillite is the sedimentary rock formed out of deposits of glaciers. The Gondawana system of sediments from India is known to have its counterparts in six different landmasses of the Southern Hemisphere. At the base the system has thick tillite indicating extensive and prolonged glaciation. Counter parts of this succession are found in Africa, Falkland Island, Madagascar, Antarctica and Australia besides India. Hence, statement 1 is correct.
• Overall resemblance of the Gondawana type sediments clearly demonstrates that these landmasses had remarkably similar histories.
• The glacial tillite provides unambiguous evidence of palaeoclimates and also of drifting of continents. Hence, statement 2 is correct.

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Correct Answer : D

Explanation

• Masses of ice moving as sheets over the land (continental glacier or piedmont glacier if a vast sheet of ice is spread over the plains at the foot of mountains) or as linear flows down the slopes of mountains in broad trough-like valleys (mountain and valley glaciers) are called glaciers
• Cirques are the most common of landforms in glaciated mountains. The cirques quite often are found at the heads of glacial valleys. The accumulated ice cuts these cirques while moving down the mountain tops. They are deep, long and wide troughs or basins with very steep concave to vertically dropping high walls at its head as well as sides. A lake of water can be seen quite often within the cirques after the glacier disappears. Such lakes are called cirque or tarn lakes. There can be two or more cirques one leading into another down below in a stepped sequence.
• When glaciers melt in summer, the water flows on the surface of the ice or seeps down along the margins or even moves through holes in the ice. These waters accumulate beneath the glacier and flow like streams in a channel beneath the ice. Such streams flow over the ground (not in a valley cut in the ground) with ice forming its banks. Very coarse materials like boulders and blocks along with some minor fractions of rock debris carried into this stream settle in the valley of ice beneath the glacier and after the ice melts can be found as a sinuous ridge called esker.
• The plains at the foot of the glacial mountains or beyond the limits of continental ice sheets are covered with glacio-fluvial deposits in the form of broad flat alluvial fans which may join to form outwash plains of gravel, silt, sand and clay. Hence, option (d) is correct.

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Correct Answer : A

Explanation

• Alluvial fans are formed when streams flowing from higher levels break into foot slope plains of low gradient. Normally very coarse load is carried by streams flowing over mountain slopes. This load becomes too heavy for the streams to be carried over gentler gradients and gets dumped and spread as a broad low to high cone shaped deposit called alluvial fan. Hence, statement 1 is correct.
• Usually, the streams which flow over fans are not confined to their original channels for long and shift their position across the fan forming many channels called distributaries.
• Alluvial fans in humid areas show normally low cones with gentle slope from head to toe and they appear as high cones with steep slope in arid and semi-arid climates. Hence, statement 2 is NOT correct.

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Correct Answer : C

Explanation

• Deposition develops a floodplain just as erosion makes valleys. Floodplain is a major landform of river deposition. Hence, statement 1 is correct.
• Large sized materials are deposited first when stream channel breaks into a gentle slope. Thus, normally, fine sized materials like sand, silt and clay are carried by relatively slow moving waters in gentler channels usually found in the plains and deposited over the bed and when the waters spill over the banks during flooding above the bed. A river bed made of river deposits is the active floodplain.
• The floodplain above the bank is inactive floodplain. Inactive floodplain above the banks basically contain two types of deposits — flood deposits and channel deposits.
• In plains, channels shift laterally and change their courses occasionally leaving cut-off courses which get filled up gradually. Such areas over flood plains built up by abandoned or cut-off channels contain coarse deposits.
• The flood deposits of spilled waters carry relatively finer materials like silt and clay. The floodplains in a delta are called delta plains.
• Natural levees and point bars are some of the important landforms found associated with floodplains. Hence, statement 2 is correct.
• Natural levees are found along the banks of large rivers. They are low, linear and parallel ridges of coarse deposits along the banks of rivers, quite often cut into individual mounds.
• During flooding as the water spills over the bank, the velocity of the water comes down and large sized and high specific gravity materials get dumped in the immediate vicinity of the bank as ridges. They are high nearer the banks and slope gently away from the river.
• The levee deposits are coarser than the deposits spread by flood waters away from the river. When rivers shift laterally, a series of natural levees can form.
• Point bars are also known as meander bars. They are found on the convex side of meanders of large rivers and are sediments deposited in a linear fashion by flowing waters along the bank.
• They are almost uniform in profile and in width and contain mixed sizes of sediments. If there more than one ridge, narrow and elongated depressions are found in between the point bars. Rivers build a series of them depending upon the water flow and supply of sediment. As the rivers build the point bars on the convex side, the bank on the concave side will erode actively.

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Correct Answer : D

Explanation

• Landscape evolution in deserts is primarily concerned with the formation and extension of pediments.
• Gently inclined rocky floors close to the mountains at their foot with or without a thin cover of debris, are called pediments. Hence, statement 1 is NOT correct.
• Such rocky floors form through the erosion of mountain front through a combination of lateral erosion by streams and sheet flooding.
• Erosion starts along the steep margins of the landmass or the steep sides of the tectonically controlled steep incision features over the landmass.
• Once, pediments are formed with a steep wash slope followed by cliff or free face above it, the steep wash slope and free face retreat backwards. This method of erosion is termed as parallel retreat of slopes through backwasting. So, through parallel retreat of slopes, the pediments extend backwards at the expense of mountain front, and gradually, the mountain gets reduced leaving an inselberg which is a remnant of the mountain. That’s how the high relief in desert areas is reduced to low featureless plains called pediplains. Thus, A pediplain is an extensive flat terrain formed by the coalescence of pediments. Hence, statement 2 is NOT correct.

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Correct Answer : B

Explanation

• Caracas officially Santiago de León de Caracas, is the capital and largest city of Venezuela, and centre of the Greater Caracas Area.
• Tripoli is the capital city and the largest city of Libya, It is located in the northwest of Libya on the edge of the desert, on a point of rocky land projecting into the Mediterranean Sea and forming a bay.
• Sana?a, also spelled Sanaa or Sana, is the largest city in Yemen and the centre of Sana?a Governorate. Under the Yemeni constitution, Sana?a is the capital of the country, although the seat of the internationally recognised government moved to Aden in the aftermath of the September 21 Revolution. Hence, option(c) is correct.

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Correct Answer : C

Explanation

• The polar vortex is a large area of low pressure and cold air surrounding both of the Earth’s poles. Hence, statement 1 is correct.
• It always exists near the poles, but weakens in summer and strengthens in winter.
• The term "vortex" refers to the counter-clockwise flow of air that helps keep the colder air near the Poles. Hence, statement 2 is correct.
• Many times during winter in the northern hemisphere, the polar vortex will expand, sending cold air southward with the jet stream. This occurs fairly regularly during wintertime and is often associated with large outbreaks of Arctic air in the United States.
• Sometimes part of this low-pressure system, break off and migrate southward, bringing all of that cold air with it.
• The breaking off of part of the vortex is what defines a polar vortex event. But it actually occurs when the vortex is weaker, not stronger. Normally, when the vortex is strong and healthy, it helps keep a current of air known as the jet stream traveling around the globe in a pretty circular path. This current keeps the cold air up north and the warm air down south.
• But without that strong low-pressure system, the jet stream doesn’t have much to keep it in line. It becomes wavy and rambling. Put a couple of areas of high-pressure systems in its way, and all of a sudden a river of cold air being pushed down south along with the rest of the polar vortex system.

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Correct Answer : C

Explanation

As per map given below option (c) is correct.

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Correct Answer : D

Explanation

• Savanna type of climate has alternate wet and dry seasons similar to monsoon climate but has considerably less annual rainfall. Also, there is no distinct rainy season like in monsoon climate. Hence, statement 1 is correct.
• It is confined within the tropics and is best developed in Sudan, hence its name the Sudan Climate. Hence, statement 2 is correct.
• It is a transitional type of climate found between the equatorial rainforests and hot deserts.
• Mean annual rainfall ranges from 80 – 160 cm [Rainfall decreases with distance from equator].
• Mean annual temperature is greater than 18° C. The monthly temperature hovers between 20° C and 32° C for lowland stations.
• Highest temperatures do not coincide with the period of the highest sun (e.g. June in the northern hemisphere) but occur just before the onset of the rainy season, i.e. April in Northern Hemisphere and October in Southern Hemisphere.
• Days are hot and nights are cold. This extreme diurnal range of temperature is another characteristic feature of the Sudan type of climate.
• The prevailing winds of the region are the Trade Winds, which bring rain to the coastal districts.
• They are strongest in the summer [favorable position of ITCZ] but are relatively dry by the time they reach the continental interiors or the western coasts [Trade winds are easterlies – flow from east to west. So rainfall decreases from east to west here].
• In West Africa, the North-East Trades, in fact, blow off-shore [continent to sea] from the Sahara Desert and reach the Guinea coast as a dry, dust-laden winds.
• On shore winds in summer bring rains and Offshore winds in winter keep the climate dry. Hence, statement 3 is correct.

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Correct Answer : A

Explanation

• Silicon and oxygen are common elements in all types of feldspar and sodium, potassium, calcium, aluminium etc. are found in specific feldspar variety. Half of the earth’s crust is composed of feldspar. It has light cream to salmon pink colour. It is used in ceramics and glass making. Hence, statement 1 is correct.
• Quartz is one of the most important components of sand and granite. It consists of silica. It is a hard mineral virtually insoluble in water. It is white or colourless and used in radio and radar. It is one of the most important components of granite. Hence, statement 2 is NOT correct.

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Correct Answer : C

Explanation

• The igneous rocks (Ignis – in Latin means ‘Fire’) are formed when magma cools and solidifies. As igneous rocks form out of magma and lava from the interior of the earth, they are known as primary rocks. Hence, statement 1 is correct.
• The process of cooling and solidification can happen in the earth’s crust or on the surface of the earth. Igneous rocks are classified based on texture.
• Texture depends upon size and arrangement of grains or other physical conditions of the materials. If molten material is cooled slowly at great depths, mineral grains may be very large. Sudden cooling (at the surface) results in small and smooth grains. Hence, statement 2 is NOT correct.
• Intermediate conditions of cooling would result in intermediate sizes of grains making up igneous rocks. Granite, gabbro, pegmatite, basalt, volcanic breccia and tuff are some of the examples of igneous rocks.
• The word ‘sedimentary’ is derived from the Latin word sedimentum, which means settling. Rocks (igneous, sedimentary and metamorphic) of the earth’s surface are exposed to denudational agents, and are broken up into various sizes of fragments. Such fragments are transported by different exogenous agencies and deposited. These deposits through compaction turn into rocks. This process is called lithification. Hence, statement 3 is correct.
• In many sedimentary rocks, the layers of deposits retain their characteristics even after lithification. Hence, we see a number of layers of varying thickness in sedimentary rocks like sandstone, shale etc.
• Depending upon the mode of formation, sedimentary rocks are classified into three major groups: (i) mechanically formed — sandstone, conglomerate, limestone, shale, loess etc. are examples; (ii) organically formed— geyserite, chalk, limestone, coal etc. are some examples; (iii) chemically formed — chert, limestone, halite, potash etc. are some examples.

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Correct Answer : C

Explanation

• The River Thames known alternatively in parts as the Isis, is a river that flows through southern England including London
• The Don is one of the major Eurasian rivers of Russia and the fifth-longest river in Europe.
• The Danube is Europe's second longest river, after the Volga. It is located in Central and Eastern Europe
• The Seine is a 777-kilometre-long river and an important commercial waterway within the Paris Basin in the north of France.
• As per Map given below option (c) is correct.

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Correct Answer : D

Explanation

• The river systems of India can be classified into four groups viz., (i) Himalayan rivers, (ii) Deccan rivers, (iii) Coastal rivers and (iv) Rivers of the inland drainage basin.
• The Himalayan rivers are formed by melting snow and glaciers and therefore, continuously flow throughout the year.
• The Deccan rivers on the other hand are rain-fed and therefore fluctuate in volume. Many of these are non-perennial.
• The Coastal streams, especially on the west coast are short in length and have limited catchment areas. Most of them are non-perennial.
• The streams of inland drainage basin of western Rajasthan are few and far apart. Most of them are of an ephemeral character
• A few rivers in Rajasthan do not drain into the sea. They drain into salt lakes and get lost in sand with no outlet to sea.
• Besides these, there are the desert rivers which flow for some distance and are lost in the desert. These are Luni, Machhu, Rupen, Saraswati, Banas, Ghaggar and others. Hence, option (d) is correct.

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Correct Answer : A

Explanation

• Lake Albert, also Mwitanzige and formerly Lake Mobutu Sese Seko, is a lake located in Uganda and the Democratic Republic of the Congo. It is one of the African Great Lakes
• Lake Victoria, also called Victoria Nyanza, largest lake in Africa and chief reservoir of the Nile, lying mainly in Tanzania and Uganda but bordering on Kenya. Lake Victoria is one of the African Great Lakes.
• Lake Tanganyika is an African Great Lake. It is the second oldest freshwater lake in the world, the second largest by volume, and the second deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. The lake is divided among four countries – Tanzania, Democratic Republic of the Congo (DRC), Burundi, and Zambia, with Tanzania (46%) and DRC (40%) possessing the majority of the lake.
• Lake Malawi, also known as Lake Nyasa in Tanzania and Lago Niassa in Mozambique, is an African Great Lake and the southernmost lake in the East African Rift system, located between Malawi, Mozambique and Tanzania.
• As per map given below, option (a) is correct.

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Correct Answer : C

Explanation

• Primary activities include agriculture, animal husbandry, forestry, fishing, mining and quarrying etc.
• Secondary activities include manufacturing industry, building and construction work etc.
• Tertiary activities include transport, communications, commerce, administration and other services.
• The Quaternary sector is an improved form of tertiary sector as it involves the services related to the knowledge sector, which includes the demand for the information- based services like taking the consultancy from tax managers, statisticians and software developers. The services involved in this type of economy are outsourced in varied forms as the doctor’ services, elementary schools and university classrooms, theaters, and brokerage firms.
• Professions of the people working in Quinary Sector are generally referred to as "gold collar" professions since the services included in the sector focus on interpretation of existing or the new ideas, evaluation of new technologies, and the creation of services. It is also one of the parts of the tertiary sector, but it involves highly paid professionals, research scientists, and government officials. The people are designated with high positions and powers, and those who make important decisions that are especially far-reaching in the world around them often belong to this category. Hence, option (c) is correct.

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Correct Answer : D

Explanation

The US has announced that it will terminate India’s designation as a beneficiary of its Generalized System of Preferences (GSP).

• Apart from India, US has also decided to withdraw Turkey from the list of GSP beneficiaries.

What is GSP?

• The idea of granting developing countries preferential tariff rates in the markets of industrialized countries was originally presented at the first UNCTAD conference in 1964. Hence, Option (d) is correct.
• The GSP was adopted at UNCTAD in New Delhi in 1968 and was instituted in 1971.
• There are currently 13 national GSP schemes notified to the UNCTAD secretariat.
• The following countries grant GSP preferences: Australia, Belarus, Canada, the European Union, Iceland, Japan, Kazakhstan, New Zealand, Norway, the Russian Federation, Switzerland, Turkey and the United States of America.
• GSP is the largest and oldest U.S. trade preference program. Established by the Trade Act of 1974, GSP promotes economic development by eliminating duties on thousands of products when imported from one of 120 designated beneficiary countries and territories.

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Correct Answer : A

Explanation

• National Rural Economic Transformation Project (NRETP) is a project under the Deendayal Antyodaya Yojana National Rural Livelihoods Mission (DAY-NRLM). A key focus of the project will be to promote women-owned and women-led farm and non-farm enterprises across value chains; enable them to build businesses that help them access finance, markets and networks; and generate employment. Hence, statement 1 is correct.
• It has been launched by the Ministry of Rural Development. Hence, statement 2 is not correct.

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Correct Answer : C

Explanation

• World Drug Report is released by the United Nations Office on Drugs and Crime which is a United Nations office that was established in 1997.
• It acts as the Office for Drug Control and Crime Prevention by combining the United Nations International Drug Control Program (UNDCP) and the Crime Prevention and Criminal Justice Division in the United Nations Office at Vienna. Hence, option (c) is correct.

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Correct Answer : C

Explanation

• The CAR is a measure of a bank's available capital expressed as a percentage of a bank's risk-weighted credit exposures.
• The Capital Adequacy Ratio, also known as capital-to-risk weighted assets ratio (CRAR), is used to protect depositors and promote the stability and efficiency of financial systems around the world. Hence, statement 1 is correct.
• Under Basel III norms, the minimum capital adequacy ratio that banks must maintain is 8%. Hence, statement 2 is also correct.

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Correct Answer : C

Explanation

• Open Market Operations (OMO) is one of a quantitative monetary policy tool (to regulate or control the total volume of money) which is an employed by the central bank of a country to control the money supply in the economy.
• Open market operations are conducted by the RBI by way of sale or purchase of government securities (g-secs) to adjust money supply conditions. Hence, option (c) is correct.

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