Solution (c)

Statement Analysis:

Solution (c)

Statement Analysis:

Solution (c)

Basic Info:

-Paleomagnetism is the study of magnetic rocks and sediments to record the history of the magnetic field. Some rocks and materials contain minerals that respond to the magnetic field. So, when rocks form, the minerals align with the magnetic field preserving its position.

–According to it, the changes in temperature and convection currents at the core determine fluctuations in earth’s magnetic field.

-A more detailed record of Earth’s magnetic past provides answers regarding the formation of the continents as well as the behavior of our magnetic field.

– Paleomagnetism also provides evidence to support theories in plate tectonics, because the ocean floor is mostly composed of basalt, an iron-rich substance containing minerals that align with the magnetic field.

-Earth’s magnetic field has flipped and reversed in the past. Based on magnetic records, the last magnetic pole shift occurred 7, 81, 000 years ago. Earth’s magnetic field also fluctuates in strength every once in a while due to changes in temperature and convection currents at the outer core.

Solution (d)

Basic Info:

– On the surface of the limestone are numerous swallow holes, which are small depressions carved out by solution where rain-water sinks into the limestone at a point of weakness. They are also known as sink holes.

– Once the water has sunk into the limestone, it etches out caverns and passages along
joints or bedding planes.  Where a number of swallow holes coalesce, a larger hollow is formed and is called a Doline.

– Several Dolines may merge as a result of subsidence to form long, narrow to wide trenches called Valley sinks or Uvala.

– Gradually, most of the surface of the limestone is eaten away by these pits and trenches, leaving it extremely irregular with a maze of points, grooves and ridges or Lapies. Especially, these ridges or lapies form due to differential solution activity along parallel to sub-parallel joints.

– The lapie field may eventually turn into somewhat smooth limestone pavements.

Solution (b)

Statement Analysis:

Solution (b)

Statement Analysis:

Solution (c)

Basic Info:

Diastrophism, also called tectonism, is a large-scale deformation of Earth’s crust by natural processes, which leads to the formation of continents and ocean basins, mountain systems, plateaus, rift valleys, and other features by mechanisms such as lithospheric plate movement (that is, plate tectonics), volcanic loading, or folding. 

It includes:

• Orogenic processes involving mountain building through severe folding and affecting long and narrow belts of the earth’s crust.
• Epeirogenic processes involving uplift or warping of large parts of the earth’s crust;

Earthquakes involving local relatively minor movements;

Plate tectonics involving horizontal movements of crustal plates.

The heat generation by the radioactive elements in earth’s interior leads to movements of Magma and tectonic activities.

Diastrophism is an endogenic geomorphic processes, while weathering, mass wasting, erosion and deposition are exogenic geomorphic processes.

Solution (c)

Basic Info:

– 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. The lava that cools within the crustal portions assumes different forms. These forms are called intrusive forms. They are:

– Batholiths: 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. 

– Lacoliths: These 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.

– Lapolith, Phacolith and Sills: As and when the lava moves upwards, a portion of the same may tend to move in a horizontal direction wherever it finds a weak plane. It may get rested in different forms. In case it develops into a saucer shape, concave to the sky body, it is called lapolith. A wavy mass of intrusive rocks, at times, is found at the base of synclines or at the top of anticline in folded igneous country. Such wavy materials have a definite conduit to source beneath in the form of magma chambers (subsequently developed as batholiths). These are called the phacoliths. 

The near horizontal bodies of the intrusive igneous rocks are called sill or sheet, depending on the thickness of the material. The thinner ones are called sheets while the thick horizontal deposits are called sills. 

– Dykes: When the lava makes its way through cracks and the fissures developed in the land, it solidifies almost perpendicular to the ground. It gets cooled in the same position to develop a wall-like structure. Such structures are called dykes. Hence option 4 is correct.

– The formation of landforms by cooling of lava on reaching the surface are called Extrusive landforms. Some of them include Lava Mesa, Lava Plateau, Cinder Cone etc.

Solution (b)

Statement Analysis:

Solution (c)

The plain is an area of lowland, either level or undulating. It seldom raises more than a
few hundred feet above sea level. There may be low hills above sea level. 

Statement Analysis:

Solution (a)

Important minor plates

 Cocos plate : Between Central America and Pacific plate
Nazca plate : Between South America and Pacific plate
Arabian plate : Mostly the Saudi Arabian landmass
Philippine plate : Between the Asiatic and Pacific plate
Caroline plate : Between the Philippine and Indian plates
Fuji plate: North-east of Australia.

Solution (c)

Important points:

-This theory was proposed by Harry Hess.

-The force of the Sea floor spreading was found to be Convective current as postulated by Arthur Holmes.

– Magma continuously wells upwards at the mid-oceanic ridges producing currents of magma flowing in opposite directions and thus generating the forces that pull the sea floor apart at
the mid-oceanic ridges.

– As the ocean floor is spread apart, cracks appear in the middle of the ridges allowing molten magma to surface through the cracks to form the newest ocean floor. Here, new crust is
generated.

– As the ocean floor moves away from the midoceanic ridge eventually comes into contact with a continental plate at convergent boundary, subducted underneath the continent and the crustal mass is consumed here.

– Finally, the lithosphere drives back into the asthenosphere where it returns to a heated state.

Solution (a)

Basic Info:

An earthquake in simple words is shaking of the Earth. It is a natural event, caused due to the release of energy, which generates waves that travel in all directions. All natural earthquakes take place in the lithosphere.

Earthquake Waves: 

The Earthquakes Waves are recorded on the seismograph.  There are basically two types of Earthquake Waves – Body waves and surface waves.

Body waves are generated at the focus and move in all the directions through the body of the Earth (3-dimensional). They are the fastest in reaching to the surface.

They are of two types which are: Primary waves/ P-waves and Secondary waves/S waves.

Primary waves/P-waves: P-waves moves longitudinally i.e. the propagation and vibration are in a same direction similar to the sound waves. They are the fastest of all the earthquake waves.
They travel through gaseous, liquid and solid materials.

Secondary waves/S-waves: S-waves are second to reach at the surface after P-waves. As they can travel only through solid materials of the Earth, they cannot pass through Earth’s outer core, therefore their shadow zone is broader than that of P-waves. This reveals that the outer core of the Earth is not in solid form.

S-waves propagate transversally i.e. the direction of propagation and the direction of vibration is perpendicular to each other.

Surface waves are generated when the body waves interact with the surface rocks.

As they move along the surface and the direction of the vibration is perpendicular to the propagation, these waves are considered as the most damaging one.

Solution (a)

Basic Info:

Earth’s Crust: It is the outermost solid part of the earth. It is brittle in nature. The thickness of
the crust varies under the oceanic and continental areas. Oceanic crust is thinner as compared to the continental crust. The thickness of the oceanic crust is 5km whereas that of the continental crust is around 30 km.

The continental crust is thicker in the areas of major mountain systems. It is as much
as 70 to 100 km thick in the Himalayan region.

The upper part of the crust consists of granite rocks and forms the continents. Its main minerals constitutes are silica and alumina. The lower part of the crust consists of basaltic rocks forming the ocean floors, comprising mainly silica, iron, and magnesium.

Mohorovicic (Moho) discontinuity forms the boundary between crust and mantle. 

The Asthenosphere is a weak zone of Earth’s Mantle and not of the Earth’s crust. Its upper layer of the earth’s mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection, is thought to occur.

Solution (a)

Basic Info:

Metamorphic Rocks:  The word metamorphic means ‘change of form’. These rocks form under the action of Pressure, Volume, and Temperature (PVT) change.

Igneous rocks form out of magma and lava from the interior of the earth.

Metamorphism occurs when rocks are forced down to lower levels by tectonic processes or when molten magma rising through the crust comes in contact with the crustal rocks or the underlying rocks are subjected to great amounts of pressure by overlying rocks.

Mechanical disruption and reorganization of the original minerals within rocks due to breaking and crushing without any appreciable chemical changes is called dynamic metamorphism. The materials of rocks chemically alter and recrystallize due to thermal metamorphism.

In the process of metamorphism, some rocks grains or minerals get arranged in layers or lines. Such an arrangement of minerals or grains in metamorphic rocks is called foliation or lineation.

Sometimes minerals or materials of different groups are arranged into alternating thin to thick layers appearing in light and dark shades. Such a structure in metamorphic rocks is called banding.

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

Solution (d)

Basic Info:

• A lake (from Latin lacus) is a large body of water (larger and deeper than a pond) within a body of land.
• As a lake is separated from the ocean, it is not a sea.
• Some lakes are very big, and people in the past sometimes called them seas.
• Lakes do not flow like rivers, but many have rivers flowing into and out of them.
• Most lakes on the surface of the Earth are fresh water and most are in the Northern Hemisphere.
• The largest lake in the world by area is the Caspian Sea, with 394,299 km².
• The largest freshwater lake by area is Lake Superior (82,414 km²), part of the Great Lakes.

Solution (c)

Basic Info:

Endogenic Processes:  The energy emanating from within the earth is the main force behind
endogenic geomorphic processes.

This energy is mostly generated by radioactivity, rotational and tidal friction and primordial heat from the origin of the earth.

This energy due to geothermal gradients and heat flow from within induces diastrophism and volcanism in the lithosphere.

Due to variations in geothermal gradients and heat flow from within, crustal thickness and strength, the action of endogenic forces are not uniform and hence the tectonically controlled original crustal surface is uneven.

Solution (c)

Basic Info:

Erosional Landforms:

– Gorges are formed due to active down cutting of the valleys through the mechanism of pothole drilling during juvenile (youth) stage of the fluvial cycle of erosion. Gorges are also formed due to recession of waterfalls. Most of the Himalayan Rivers have carved out deep and narrow gorges.

– Waterfalls are caused because of sudden descents or abrupt breaks in the longitudinal
course of the rivers due to a host of factors like variation in the relative resistance of rocks, relative difference in topographic reliefs, fall in the sea level and related rejuvenation, earth movements, etc. A waterfall may be defined as a vertical drop of water of enormous volume from a great height in the long profiles of the rivers. Rapids are of much smaller dimension than waterfalls.

– The kettle-like small depressions in the rocky beds of the river valleys are called potholes which are usually cylindrical in shape. Potholes are generally formed in coarse-grained rocks such as sandstones and granites.

Solution (d)

Basic Info:

Plate Tectonic Theory:

– A plate is a rigid lithospheric slab in the earth surface. If two tectonic plates collide, they form a convergent plate boundary. Usually, one of the converging plates will move beneath the other, which is known as subduction. Deep trenches are often formed where tectonic plates are being subducted and earthquakes are common.

– Plate tectonics theory deals with the dynamics of Earth’s outer shell known as the lithosphere that provides an understanding for mountain-building processes, volcanoes, and earthquakes as well as the evolution of Earth’s surface and reconstructing its past continents and oceans.

– According to the theory, the lithosphere, is about 100 km (60 miles) thick and overlies a plastic (moldable, partially molten) layer called the asthenosphere. The lithosphere is broken up into several plates which move relative to each other.

– Convection currents beneath the plates move the crustal plates in different directions. The source of heat driving the convection currents is radioactivity deep in the Earth’s mantle. They are believed to cause Paleomagnetism in the earth surface around the poles.

– In Convergent plate boundary, two lithospheric plates collide against each other and the zone of collision may undergo crumpling and folding and folded mountains may emerge. This is an orogenic collision. Himalayan Boundary Fault is one such example. When one of the plates is an
oceanic plate, it gets embedded in the softer asthenosphere of the continental plate and as a result, trenches are formed at the zone of subduction. The subducted material gets heated, up and is thrown out forming volcanic islands and dynamic equilibrium is achieved.

– Divergent plate Boundary: As the name itself suggests, in this kind of interaction, the plates diverge [move away from each other]. Mid-oceanic ridges are formed due to this kind of interaction. Here, the basaltic magma erupts and moves apart (sea floor spreading).

– On continents, East African Rift Valley is the most important geomorphological feature formed due to divergence of African and Somali plates. Such edges are sites of earth crust formation (hence constructive) and volcanic earth forms are common along such edges.

– Transform plate boundary: It is formed when two plates move past each other. In this kind of interaction, two plates grind against each other and there is no creation or destruction of landform but only deformation of the existing landform. [Crust is neither produced nor destroyed as the plates slide horizontally past each other].

Solution (d) 

All are causes of tsunami

Basic Info:

A tsunami is a series of large waves usually noticed on sea or ocean surfaces that can lead to a considerable amount of loss to life and property. It is a sudden displacement of water that can take place in any waterbody if underlying causes are present there.

Causes:

Earthquakes:  The Earth’s surface is made up of tectonic plates and when these plates undergo any tectonic activity (spreading, subduction and transformation), they can lead to tsunamis. However, all earthquakes do not cause a tsunami. 

Volcanic eruption: Volcanic explosions cause impulsive disturbances and thus can displace a large volume of water generating extensive tsunamis.

Landslides: Landslides occurring along the coasts can force a large amount of water into the sea thus causing a disturbance in water resulting in a tsunami.

Extra-terrestrial occurrences: A tsunami caused by extra-terrestrial collisions has not taken place in recent history but it is believed that if celestial bodies like asteroids or meteors strike the ocean, a large volume of water would be displaced causing a tsunami.

Solution (a)

Statement Analysis:

Context- People’s Plan Campaign (PPC) was recently launched by Ministry of Panchayati Raj

Solution (d)

Statement Analysis:

Context – Delhi High Court sought Lok Sabha Secretariat reply to a petition on the vacant post of deputy speaker for over 2 years

Solution (c)

Early harvest scheme is a precursor to an FTA between two trading partners. This is to help the two trading countries identify certain products for tariff liberalisation pending the conclusion of FTA negotiation. It is primarily a confidence building measure.

Context – India is keen to conclude an “early harvest” trade deal with some countries

Solution (d)

The Shanghai Cooperation Organization (SCO) is an intergovernmental organization founded in Shanghai on 15 June 2001. The SCO currently comprises eight Member States (China, India, Kazakhstan, Kyrgyzstan, Russia, Pakistan, Tajikistan and Uzbekistan), four Observer States interested in acceding to full membership (Afghanistan, Belarus, Iran, and Mongolia) and six “Dialogue Partners” (Armenia, Azerbaijan, Cambodia, Nepal, Sri Lanka and Turkey).

Context – 21st Meeting of Shanghai Cooperation Organization (SCO) Council of Heads of State took place 

Solution (a)

Statement Analysis:

Context – India Extended support for protecting Antarctic environment and for designating East Antarctica and Weddell Sea as Marine Protected Areas (MPAs)

Solution (c)

Sum of the terms of the ratio = 4 + 5 = 9
Sum of numbers = 63

Therefore, first number = 4/9 × 63 = 28
Second number = 5/9 × 63 = 35

Therefore, the two numbers are 28 and 35.

Solution (b)

Let the money received by Tim, Sam and Ian be 4x, 5x, 6x respectively.
Given that Ian has got $ 300.
Therefore, 6x = 300
or, x = 300/6
or, x = 50
So, Tim got = 4x
                   = $ 4 × 50 = $200

Sam got = 5x
              = 5 × 50 = $250

Therefore, the total amount $(200 + 250 + 300) = $750 

Solution (a)

Number of girls in the class = 21
Ratio of boys and girls = 4 : 3
According to the question,

Boys/Girls = 4/3
Boys/21= 4/3
Boys = (4 × 21)/3 = 28

Therefore, total number of students = 28 + 21 = 49.

Solution (b)

Let 2A = 3B = 4C = x
So, A = x/2 B = x/3 C = x/4

The L.C.M of 2, 3 and 4 is 12

Therefore, A : B : C = x/2 × 12 : x/3 × 12 : x/4 = 12

= 6x : 4x : 3x
= 6 : 4 : 3

Therefore, A : B : C = 6 : 4 : 3

Solution (c)

In the first paragraph, the author introduces the main idea. The author says, “Making the perfect pizza can be complicated, but there are lots of ways for you to make a more basic version at home.” Here, the author tells us that he or she wants to give us some ways to make a more basic pizza at home. The author spends the rest of the passage outlining the steps we need to take to make the pizza. This means option c is correct. The passage does not provide information to support choices a, b, and d. Therefore they are incorrect.