World and Physical Geography Archives

281. Which of the following statements is/are correct? 1. The Earth’s cru

Which of the following statements is/are correct?

1. The Earth’s crust is brittle in nature.
2. The mean thickness of the oceanic crust is 15 km whereas that of the continental crust is around 30 km.

Select the correct answer using the code given below.

[amp_mcq option1=”1 only” option2=”2 only” option3=”Both 1 and 2″ option4=”Neither 1 nor 2″ correct=”option1″]

This question was previously asked in

UPSC NDA-2 – 2022

Let’s analyze each statement:
1. The Earth’s crust is brittle in nature: This statement is correct. The upper part of the Earth’s crust behaves in a brittle manner, meaning it tends to break and fracture under stress rather than deform plastically. This brittle behavior is responsible for phenomena like faulting and earthquakes.
2. The mean thickness of the oceanic crust is 15 km whereas that of the continental crust is around 30 km: This statement is incorrect. The oceanic crust is significantly thinner than the continental crust. The mean thickness of the oceanic crust is typically around 5-10 km, while the mean thickness of the continental crust is around 30-40 km (and can be up to 70 km under major mountain ranges).

The Earth’s crust is the outermost solid shell of the planet and exhibits brittle characteristics, particularly near the surface. Oceanic and continental crusts differ significantly in their thickness and composition.

The oceanic crust is primarily composed of basalt and gabbro and is denser than the continental crust, which is mainly composed of granitic and andesitic rocks. This difference in density and thickness is fundamental to plate tectonics and the formation of Earth’s surface features.

282. Consider the following statements about anticyclones : 1. Anticyclon

Consider the following statements about anticyclones :

1. Anticyclones are high pressure systems.
2. Air in the centre of the system must be subsiding.
3. Anticyclones are characterized by converging winds.

How many of the above statements is/are correct?

[amp_mcq option1=”1″ option2=”2″ option3=”3″ option4=”None” correct=”option2″]

This question was previously asked in

UPSC NDA-2 – 2022

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Let’s evaluate each statement:
1. Anticyclones are high pressure systems: This is correct. Anticyclones are defined as areas of high atmospheric pressure, relative to their surroundings.
2. Air in the centre of the system must be subsiding: This is correct. High pressure at the surface is associated with descending air (subsidence) from aloft. As air descends, it warms and dries, leading to stable atmospheric conditions and often clear skies.
3. Anticyclones are characterized by converging winds: This is incorrect. Anticyclones are characterized by diverging winds at the surface, flowing outwards from the high-pressure center. In the Northern Hemisphere, these winds diverge clockwise, and in the Southern Hemisphere, they diverge counter-clockwise due to the Coriolis effect. Convergence occurs aloft above the anticyclone.

Anticyclones are stable weather systems associated with sinking air, high pressure, and diverging winds near the surface, typically bringing fair weather.

In contrast to anticyclones, cyclones (low-pressure systems) are characterized by converging winds at the surface, rising air, and often bring cloudy skies, precipitation, and unstable weather.

283. The formation of ‘tors’ on small rocky hills is associated with which

The formation of ‘tors’ on small rocky hills is associated with which among the following?

[amp_mcq option1=”Granite” option2=”Limestone” option3=”Alluvial” option4=”Dolomite” correct=”option1″]

This question was previously asked in

UPSC NDA-2 – 2022

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Tors are distinctive rock landforms that consist of outcrops of bedrock weathered into piles of rounded boulders. They are typically formed in areas underlain by igneous rocks, most commonly granite. The formation process involves the intersection of joint patterns in the granite bedrock, followed by subsurface weathering (like hydrolysis) along these joints and subsequent erosion of the weathered material, leaving the unweathered core stones exposed as tors.

Granite, being susceptible to weathering along its natural joint systems and through chemical processes like hydrolysis, provides the ideal conditions for the development of tors.

While tors are most characteristic of granite, similar landforms can occasionally develop on other jointed rock types like dolerite, but they are overwhelmingly associated with granitic landscapes. Limestone and dolomite typically form karst topography through dissolution, and alluvial deposits are unconsolidated sediments, neither of which forms tors.

284. Consider the following statements on computation of density: 1. Phys

Consider the following statements on computation of density:

1. Physiological density can be computed by dividing the total population by the net cultivable area.
2. Agricultural density can be computed by dividing the total agricultural population by the net cultivable area.
3. Population density can be computed by dividing the total population by the total area.

How many of the above statements is/are correct?

[amp_mcq option1=”1″ option2=”2″ option3=”3″ option4=”None” correct=”option3″]

This question was previously asked in

UPSC NDA-2 – 2022

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All three statements correctly define different types of population density computations.
1. Physiological density is indeed calculated by dividing the total population by the net cultivable area. This gives an idea of the pressure on arable land for food production.
2. Agricultural density is calculated by dividing the total agricultural population (farmers, farm workers, and their dependents) by the net cultivable area. This measures the number of people engaged in agriculture per unit area of arable land.
3. Population density (or Arithmetic density) is the most basic measure, computed by dividing the total population by the total land area. This indicates the average number of people per unit area.

Different measures of density provide varying insights into the relationship between population and land, highlighting aspects like resource pressure, agricultural efficiency, or simple spatial distribution.

While population density gives a general sense of crowding, physiological and agricultural densities are more specific measures related to agricultural capacity and rural population dynamics. Other density measures exist, such as urban density, which considers only urban areas.

285. Vapours of sulphur escaping from a volcano often form a crust on the r

Vapours of sulphur escaping from a volcano often form a crust on the rocks. The process involved is an example of

[amp_mcq option1=”condensation” option2=”precipitation” option3=”deposition” option4=”evaporation” correct=”option3″]

This question was previously asked in

UPSC NDA-2 – 2022

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The correct answer is deposition.

Deposition is the phase transition in which gas transforms into solid without passing through the liquid phase. Sulphur escaping from a volcano as vapour (gas) cools upon contact with rocks and directly forms a solid crust. This is the reverse of sublimation.

Condensation is the change of state from gas to liquid. Precipitation is the process of forming a solid from a solution or vapour phase, often used for meteorological phenomena (rain, snow, etc.) or chemical solid formation from a liquid. Evaporation is the change of state from liquid to gas.

286. Which one of the following statements about earthquake waves is not

Which one of the following statements about earthquake waves is not correct?

[amp_mcq option1=”P waves move faster and are the first to arrive at the surface.” option2=”P waves can travel through gaseous, liquid and solid materials.” option3=”Seismographs located beyond 145° from epicentre can record the arrival of P waves.” option4=”P waves have maximum area covered under its shadow zone.” correct=”option4″]

This question was previously asked in

UPSC NDA-2 – 2022

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Let’s examine each statement about earthquake waves:
A) P waves (Primary waves) are the fastest seismic waves and are the first to reach any point on the Earth’s surface or within it. This statement is correct.
B) P waves are compressional waves and can travel through solid, liquid, and gaseous mediums. This statement is correct.
C) Seismographs located beyond 145° from the epicenter *can* record P waves, but these are the P waves that have been refracted by the Earth’s core. There is a P-wave shadow zone between approximately 105° and 145° where direct P waves are not recorded due to refraction. Beyond 145°, refracted P waves arrive. This statement is correct.
D) The shadow zone for P waves is the area between ~105° and ~145°. S waves (Secondary waves) cannot travel through the liquid outer core, resulting in an S-wave shadow zone that starts at ~105° and extends to the entire hemisphere beyond that. Therefore, the S-wave shadow zone is much larger than the P-wave shadow zone. This statement is incorrect.

The key difference in shadow zones is that P waves are refracted by the core (creating a partial shadow zone), while S waves are stopped by the liquid outer core (creating a larger, complete shadow zone beyond 105°).

Earthquake waves provide valuable information about the Earth’s interior structure. The existence and size of the shadow zones for P and S waves were crucial in determining the presence of a liquid outer core.

287. The major portion of the Great Artesian Basin in Australia is located

The major portion of the Great Artesian Basin in Australia is located in

[amp_mcq option1=”Western Australia” option2=”Victoria” option3=”Queensland” option4=”Northern Territory” correct=”option3″]

This question was previously asked in

UPSC NDA-2 – 2022

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The Great Artesian Basin is a vast and deep groundwater basin in Australia. It underlies about 22% of the continent, including most of Queensland, the north-eastern part of South Australia, the south-eastern part of the Northern Territory, and the north-western part of New South Wales.

While the basin spans across several states and territories, the largest portion by area is located within the state of Queensland.

The Great Artesian Basin is the largest and deepest artesian basin in the world. It is a crucial water source for arid and semi-arid inland areas of Australia, supporting pastoral activities, mining, and communities. Artesian groundwater is water that rises to the surface under its own pressure.

288. Which one of the following features is the result of erosion and depos

Which one of the following features is the result of erosion and deposition work of a river?

[amp_mcq option1=”Pothole” option2=”Oxbow lake” option3=”Levee” option4=”Rapid” correct=”option2″]

This question was previously asked in

UPSC NDA-2 – 2021

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An oxbow lake is a crescent-shaped lake formed when a river meander is cut off from the main channel. This process involves erosion (cutting through the neck of the meander) and deposition (sealing off the ends of the abandoned channel).

Oxbow lakes are landforms typically found in the mature stage of a river valley, resulting from lateral erosion and deposition.

Potholes are cylindrical depressions drilled in the river bed by abrasion (erosion). Levees are natural or artificial embankments formed along the river banks by deposition of sediment. Rapids are turbulent sections of a river where the water flows rapidly over a steep gradient, primarily an erosional environment or flow characteristic rather than a depositional landform.

289. The periodic rise and fall of ocean water in response to gravitational

The periodic rise and fall of ocean water in response to gravitational forces is called

[amp_mcq option1=”Current” option2=”Waves” option3=”Tides” option4=”Tsunami” correct=”option3″]

This question was previously asked in

UPSC NDA-2 – 2021

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Tides are the periodic rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth.

Gravitational forces from the Moon and Sun are the primary drivers of tides.

Ocean currents are continuous, directed movement of sea water. Waves are disturbances on the surface of water bodies. A tsunami is a series of large waves caused by earthquakes or other underwater disturbances.

290. Which one of the following is the longest parallel of latitude ?

Which one of the following is the longest parallel of latitude ?

[amp_mcq option1=”Tropic of Cancer” option2=”Tropic of Capricorn” option3=”Arctic Circle” option4=”Equator” correct=”option4″]

This question was previously asked in

UPSC NDA-2 – 2021

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The Earth is roughly spherical, and parallels of latitude are circles drawn parallel to the Equator. The circumference of these circles decreases as they move away from the Equator towards the poles. The Equator itself is the largest circle of latitude, dividing the Earth into the Northern and Southern Hemispheres.

The Equator is the 0-degree parallel of latitude and has the largest circumference among all parallels.

The Tropic of Cancer (23.5° N), Tropic of Capricorn (23.5° S), Arctic Circle (66.5° N), and Antarctic Circle (66.5° S) are all parallels of latitude, but their lengths are progressively shorter than the Equator.