World and Physical Geography

51. Which one of the following is not a ‘cold ocean current’?

Which one of the following is not a ‘cold ocean current’?

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Benguela Current
Canary Current
Falkland Current
Kuroshio Current
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The Kuroshio Current is a warm ocean current, unlike the other options which are cold currents.
Ocean currents are classified as warm or cold based on whether they carry water from warmer regions to colder regions (warm currents) or from colder regions to warmer regions (cold currents). The Benguela Current flows northwards along the west coast of southern Africa, originating from the Southern Ocean (cold). The Canary Current flows southwards along the northwestern coast of Africa, originating from the North Atlantic (cold). The Falkland Current flows northwards along the coast of Argentina, originating from the Southern Ocean (cold). The Kuroshio Current flows northeastwards from the east coast of Taiwan towards Japan and beyond, originating from the tropics (warm).
Warm currents typically flow towards the poles along the eastern coasts of continents (except in high latitudes), while cold currents typically flow towards the equator along the western coasts of continents (except in high latitudes). These currents play a crucial role in regulating global climate and influencing marine ecosystems.

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52. Which one of the following is not a basic factor in soil formation?

Which one of the following is not a basic factor in soil formation?

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Climate
Biological activity
Human activity (agriculture)
Time
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Human activity (agriculture) is generally considered an important factor influencing soil properties and development, but not one of the five fundamental *basic* factors of soil formation.
The five generally accepted basic factors of soil formation, often remembered by the acronym CLORPT, are: CLimate, Organisms (biological activity), Relief (topography), Parent material, and Time. While human activities like agriculture significantly modify soil, they are typically categorized as external influences or pedoturbation rather than inherent basic factors that initiate or fundamentally govern soil development from parent material.
Other human activities that impact soil include deforestation, urbanization, pollution, and irrigation. These activities can accelerate or retard soil processes, alter soil structure, composition, and fertility, but they operate upon the soil-forming processes governed by the basic factors.

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53. Consider the following statements with respect to the ‘asthenosphere’

Consider the following statements with respect to the ‘asthenosphere’ :

  • 1. It extends from the lower crust to the upper mantle.
  • 2. It is the main source of the magma that finds its way to the surface of the Earth during volcanic eruptions.

Which of the statements given above is/are correct?

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1 only
2 only
Both 1 and 2
Neither 1 nor 2
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Statement 2 correctly identifies the asthenosphere as a major source of magma, while Statement 1 inaccurately describes its location.
The asthenosphere is the highly viscous, mechanically weak and ductile region of the upper mantle, below the lithosphere. It extends roughly from about 100 km to 400 km depth. Statement 1 is incorrect because the asthenosphere is entirely within the upper mantle and does not extend into the lower crust. Statement 2 is correct because partial melting occurs within the asthenosphere due to its temperature and pressure conditions, generating magma that contributes to volcanic activity.
The lithosphere, which comprises the rigid crust and uppermost part of the mantle, floats on the ductile asthenosphere. The movement of tectonic plates (parts of the lithosphere) is facilitated by the plastic flow within the asthenosphere.

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54. What is the correct chronological sequence of the following ‘periods’

What is the correct chronological sequence of the following ‘periods’ in the Earth’s geological timescale?

  • 1. Cambrian
  • 2. Carboniferous
  • 3. Cretaceous
  • 4. Devonian

Select the correct answer using the code given below.

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1-4-2-3
1-2-4-3
1-2-3-4
2-1-3-4
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The correct option is A.
The geological timescale periods mentioned belong to the Phanerozoic Eon. Their correct chronological order from oldest to youngest is:
1. **Cambrian** (Paleozoic Era, starting ~541 million years ago)
2. **Devonian** (Paleozoic Era, ~419 – 359 million years ago)
3. **Carboniferous** (Paleozoic Era, ~359 – 299 million years ago)
4. **Cretaceous** (Mesozoic Era, ~145 – 66 million years ago)
The Paleozoic Era follows the Precambrian and precedes the Mesozoic Era. The order of periods within the Paleozoic is Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian. The Mesozoic Era consists of the Triassic, Jurassic, and Cretaceous periods.

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55. Subduction zone with reference to plate tectonics is associated with w

Subduction zone with reference to plate tectonics is associated with which of the following plate boundaries?

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  • 1. Convergent boundaries
  • 2. Divergent boundaries

Select the correct answer using the code given below.

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1 only
2 only
Both 1 and 2
Neither 1 nor 2
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The correct option is A.
– Subduction zones occur at **convergent plate boundaries** where one tectonic plate slides beneath another plate into the Earth’s mantle. This typically happens when an oceanic plate converges with a continental plate or another oceanic plate.
– Divergent plate boundaries are where plates move apart, leading to the creation of new crust (e.g., mid-ocean ridges). Subduction does not occur at divergent boundaries.
Convergent boundaries can also result in continental collision (e.g., formation of Himalayas) where subduction may not occur or is incomplete. Subduction zones are associated with deep ocean trenches, volcanic arcs, and significant seismic activity.

56. Which one of the following is not a factor that causes variations in

Which one of the following is not a factor that causes variations in ‘insolation’?

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Rotation of the Earth on its axis
Angle of inclination of the Sun's rays
Length of the day
Vegetation cover on the Earth's surface
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The correct option is D.
– Rotation of the Earth on its axis causes the daily cycle of day and night, leading to daily variations in insolation received at any point.
– Angle of inclination of the Sun’s rays varies with latitude and season (due to Earth’s tilt), affecting the intensity of insolation received per unit area. Lower angles (higher latitudes/winter) result in less intense insolation.
– Length of the day varies with latitude and season, determining the duration for which insolation is received, thus affecting the total amount of insolation received daily.
– Vegetation cover on the Earth’s surface affects how much of the received insolation is absorbed, reflected (albedo), or used in processes like transpiration. It does **not** affect the amount of insolation arriving from the sun at the top of the atmosphere or at the surface before interaction with the cover.
Factors affecting insolation received from the sun include solar constant, distance from the sun (Earth’s elliptical orbit), angle of incidence of sun’s rays (latitude, season, time of day), length of the day, and atmospheric transparency (clouds, aerosols, gases). Vegetation affects the Earth’s energy balance *after* insolation arrives.

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57. Which one of the following is not an erosional landform?

Which one of the following is not an erosional landform?

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Esker
Pediment
Point bar
Stack
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The correct option is C.
– Esker: A long, winding ridge composed of stratified sand and gravel, deposited by glacial meltwater streams flowing in tunnels within or under a glacier. This is a **depositional** landform.
– Pediment: A broad, gently sloping erosional surface cut into bedrock or thin veneer of alluvium at the foot of a mountain front in arid or semi-arid regions. This is primarily an **erosional** landform.
– Point bar: An alluvial deposit that accumulates on the inside bend of a meandering stream or river. This is a **depositional** landform.
– Stack: A geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coastline, formed by wave erosion. This is an **erosional** landform.
The question asks which one is *not* an erosional landform. Both Esker and Point bar are depositional landforms and therefore fit this description. Given that only one option can be selected, there might be an issue with the question having two correct answers among the options provided (A and C). However, following standard classifications, both are definitively non-erosional (i.e., depositional). If forced to choose one, or assuming a single correct answer is expected, both A and C represent landforms primarily built by deposition of sediment rather than sculpted by erosion. Without further context or clarification, both A and C are technically correct. Based on a common understanding and prominent examples, both Esker (glacial deposition) and Point Bar (fluvial deposition) are key depositional features.

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58. Consider the following statements: 1. The point where energy is rele

Consider the following statements:

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  • 1. The point where energy is released is called hypocentre.
  • 2. The point on the surface nearest to the focus is called epicentre.

Which of the statements given above is/are correct?

1 only
2 only
Both 1 and 2
Neither 1 nor 2
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The correct option is C.
– Statement 1 is correct: The hypocentre (also known as the focus) is the point within the Earth where an earthquake rupture starts and energy is released.
– Statement 2 is correct: The epicentre is the point on the Earth’s surface directly above the hypocentre (focus), and it is usually the point where the earthquake effects are strongest. It is indeed the point on the surface nearest to the focus.
Seismic waves radiate outwards from the hypocentre. The intensity of the earthquake is typically highest near the epicentre.

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59. The longest border between any two countries in the world is between :

The longest border between any two countries in the world is between :

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Canada and the United States of America.
Chile and Argentina
China and India
Kazakhstan and Russian Federation
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The longest international border between any two countries in the world is shared by Canada and the United States of America. This border is approximately 8,891 kilometers (5,525 miles) long.
– The Canada-USA border consists of two sections: the southern border shared with the contiguous United States and the western border shared with Alaska.
– Other long borders include Kazakhstan-Russia (approx. 7,644 km), Argentina-Chile (approx. 5,308 km), and China-India (approx. 3,488 km, includes disputed areas).
– The Canada-USA border is also known as the longest undefended border in the world.
Length of borders mentioned:
– Canada-USA: ~8,891 km
– Chile-Argentina: ~5,308 km
– China-India: ~3,488 km
– Kazakhstan-Russian Federation: ~7,644 km
Comparing these lengths confirms that the Canada-USA border is the longest.

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60. Consider the following statements : The Red Sea receives very little

Consider the following statements :

  • The Red Sea receives very little precipitation in any form.
  • No water enters the Red Sea from rivers.

Which of the statements given above is/are correct ?

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1 only
2 only
Both 1 and 2
Neither 1 nor 2
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The correct option is C, as both statements are correct.
Statement 1 is correct because the Red Sea region is characterized by an arid to semi-arid climate with very low average annual precipitation. Statement 2 is also correct because the land areas surrounding the Red Sea are predominantly desert, lacking any major perennial rivers that would flow into the sea. The primary source of water input to the Red Sea is through exchange with the Gulf of Aden and evaporation is very high, leading to high salinity.
Due to limited precipitation and lack of riverine input combined with high evaporation rates, the Red Sea is one of the warmest and saltiest seas in the world. The primary water exchange occurs at its southern end through the Bab-el-Mandeb strait, connecting it to the Gulf of Aden and the Indian Ocean.

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