IAS EXPRESS Vs UPSC Prelims 2024

Statement-1: The atmosphere is heated more by incoming solar radiation than by terrestrial radiation. Statement-II: Carbon dioxide and other greenhouse gases in the atmosphere are good absorbers of long wave radiation.

Which one of the following is correct in respect of the above statements?
(a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
(c) Statement-I is correct, but Statement-II is incorrect
(d) Statement-I is incorrect, but Statement-II is correct

Explanation

The correct answer is: (d) Statement-I is incorrect, but Statement-II is correct.

• Statement-I is incorrect: The atmosphere is not heated more by incoming solar radiation than by terrestrial radiation. Instead, it is mainly heated by long wave terrestrial radiation. The Earth’s surface absorbs shortwave solar radiation and re-radiates it as longwave infrared radiation, which is then absorbed by greenhouse gases in the atmosphere, heating it from below.
• Statement-II is correct: Carbon dioxide and other greenhouse gases in the atmosphere are indeed good absorbers of long wave radiation. These gases absorb the infrared radiation emitted by the Earth’s surface and re-radiate it, contributing to the warming of the atmosphere.

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• Terrestrial Radiation:
  • The Earth receives solar energy in the form of shortwave radiation.
  • After absorbing this energy, the Earth re-radiates it as longwave infrared radiation.
  • This longwave radiation is absorbed by atmospheric gases, particularly carbon dioxide and other greenhouse gases.
  • This process is known as terrestrial radiation and is the primary way the atmosphere is heated.
• Greenhouse Effect:
  • Greenhouse gases such as water vapor, carbon dioxide, methane, and others absorb longwave infrared radiation emitted by the Earth’s surface.
  • These gases then re-radiate the energy in all directions, including back towards the Earth’s surface, creating a warming effect known as the greenhouse effect.
  • This effect is crucial for maintaining the Earth’s temperature, making it habitable.
• Insolation:
  • Insolation refers to the incoming solar radiation that reaches the Earth’s surface.
  • The atmosphere is largely transparent to this shortwave solar radiation, allowing it to pass through and be absorbed by the Earth’s surface.
  • However, the atmosphere absorbs only a small fraction of this shortwave radiation directly.
• Energy Balance:
  • The Earth’s energy balance involves the absorption of solar radiation and the emission of terrestrial radiation.
  • Approximately 30% of incoming solar radiation is reflected back to space, while the remaining 70% is absorbed by the Earth’s surface and atmosphere.
  • The absorbed energy is eventually re-radiated as longwave infrared radiation, which is then absorbed by greenhouse gases, maintaining the Earth’s energy balance and temperature.
• Role of Greenhouse Gases:
  • Water vapor and carbon dioxide are the most significant greenhouse gases in terms of their ability to absorb and re-radiate infrared radiation.
  • These gases trap heat within the atmosphere, preventing it from escaping into space, thus warming the planet.
  • Without the natural greenhouse effect, the Earth’s average temperature would be significantly lower, making it less hospitable for life.

By understanding these processes, it becomes clear that the atmosphere is primarily heated by terrestrial radiation rather than direct solar radiation, and greenhouse gases play a crucial role in this heating mechanism.

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Statement-I: Thickness of the troposphere at the equator is much greater as compared to poles.

Statement-II: At the equator, heat is transported to great heights by strong convectional currents.

Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II’ are correct and Statement-II explains Statement-I

(b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I

(c) Statement-I is correct, but Statement-II is incorrect

(d) Statement-I is incorrect, but Statement-II is correct

Explanation

Correct Answer: (a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I

• Statement-I: The thickness of the troposphere at the equator is much greater as compared to the poles.
  • This statement is correct. The troposphere is thicker at the equator due to higher temperatures, which cause thermal expansion and stronger convectional currents that push the troposphere to greater heights.
• Statement-II: At the equator, heat is transported to great heights by strong convectional currents.
  • This statement is correct. The equator receives more solar radiation, leading to higher temperatures and stronger convectional currents that transport heat to higher altitudes.
• Explanation: Statement-II explains Statement-I because the strong convectional currents at the equator, driven by higher temperatures, result in the expansion of the troposphere, making it thicker at the equator compared to the poles.

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• Troposphere: The troposphere is the lowest layer of Earth’s atmosphere, extending from the surface to an average height of about 8 km at the poles and 18 km at the equator.
• Thermal Expansion: The equator is warmer, causing the air to expand and rise, leading to a thicker troposphere.
• Convectional Currents: Strong convectional currents at the equator transport heat to great heights, contributing to the increased thickness of the troposphere.
• Centrifugal Force: The Earth’s rotation causes a centrifugal force that is strongest at the equator, pushing the atmosphere to greater heights.
• Seasonal Variation: The thickness of the troposphere varies with the seasons, being thicker in the summer and thinner in the winter.
• Gravitational Pull: The gravitational pull is stronger at the poles, leading to a contraction of the atmosphere and a thinner troposphere.

These factors collectively explain why the troposphere is thicker at the equator than at the poles.

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1. Pyroclastic debris
2. Ash and dust
3. Nitrogen compounds
4. Sulphur compounds

How many of the above are products of volcanic eruptions?

(a) Only one
(b) Only two
(c) Only three
(d) All four

Explanation

Correct Answer: (d) All four

• Pyroclastic debris: These are fragments of rock ejected during explosive volcanic eruptions. They include various sizes of particles such as ash, lapilli, blocks, and bombs.
• Ash and dust: Volcanic ash consists of fine particles of pulverized rock, minerals, and volcanic glass created during explosive eruptions. These particles can be carried by wind over large distances.
• Nitrogen compounds: Volcanic lightning during eruptions can fix atmospheric nitrogen into bioavailable forms such as nitrate. This process involves the breaking of the dinitrogen bond and subsequent reactions with oxygen.
• Sulphur compounds: Volcanic eruptions release gases such as sulfur dioxide (SO2) and hydrogen sulfide (H2S). These gases can form sulfuric acid and other sulfur compounds in the atmosphere.

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• Pyroclastic debris:
  • Definition: Fragments of rock ejected during explosive volcanic eruptions.
  • Types: Includes ash (particles <2 mm), lapilli (2-64 mm), blocks (angular fragments >64 mm), and bombs (rounded fragments >64 mm).
  • Formation: Created by the violent expansion of gas that shreds magma into small particles.
• Ash and dust:
  • Definition: Fine particles of pulverized rock, minerals, and volcanic glass.
  • Dispersal: Can be carried by wind over large distances, affecting areas far from the eruption site.
  • Impact: Can cause respiratory issues, damage machinery, and disrupt transportation and communication systems.
• Nitrogen compounds:
  • Formation: Created by volcanic lightning, which breaks the dinitrogen bond in the atmosphere.
  • Types: Includes nitrate and ammonia, which are essential for biological processes.
  • Role in prebiotic chemistry: Volcanic lightning may have contributed to the synthesis of nitrogen compounds necessary for the emergence of life.
• Sulphur compounds:
  • Types: Includes sulfur dioxide (SO2) and hydrogen sulfide (H2S).
  • Sources: Emitted from volcanic vents, fumaroles, and during eruptions.
  • Impact: Can form sulfuric acid in the atmosphere, contributing to acid rain and affecting climate.

All four options listed are indeed products of volcanic eruptions, confirming the correct answer is (d) All four.

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1. The isotherms deviate to the north over the ocean and to the south over the continent.
2. The presence of cold ocean currents, Gulf Stream and North Atlantic Drift make the North Atlantic Ocean colder and the isotherms bend towards the north.

Select the answer using the code given below:

(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Explanation

The correct answer is (a) 1 only.

• Statement 1: The isotherms deviate to the north over the ocean and to the south over the continent. This is correct. In January, the isotherms bend northward over the oceans due to the warming effect of warm ocean currents like the Gulf Stream and North Atlantic Drift, and they bend southward over the continents due to the cooling effect of the landmasses.
• Statement 2: The presence of cold ocean currents, Gulf Stream, and North Atlantic Drift make the North Atlantic Ocean colder and the isotherms bend towards the north. This is incorrect. The Gulf Stream and North Atlantic Drift are warm ocean currents, not cold. They warm the Northern Atlantic Ocean, causing the isotherms to bend northward, indicating warmer temperatures.

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• Isotherms: Lines on a map connecting points with the same temperature at a given time or over a specified period. They are used in meteorology to depict temperature distribution.
• January Temperature Distribution:
  • Northern Hemisphere: Isotherms deviate north over the ocean due to warm currents like the Gulf Stream and North Atlantic Drift, and south over the continents due to the cooling effect of landmasses.
  • Southern Hemisphere: Isotherms are more parallel to latitudes due to the ocean’s moderating effect, leading to more gradual temperature variations.
• Factors Influencing Isotherms:
  • Latitude: Temperature generally decreases from the equator to the poles.
  • Land and Water: Land heats and cools more rapidly than water, causing deviations in isotherms.
  • Ocean Currents: Warm currents (e.g., Gulf Stream) cause northward bends, while cold currents cause southward bends.
  • Topography: Mountains and valleys can affect local temperature distributions, causing deviations in isotherms.
• Seasonal Variations:
  • January: More pronounced deviations in the northern hemisphere due to larger landmasses and significant temperature differences between land and sea.
  • July: Isotherms generally follow latitudes more closely, with less pronounced deviations compared to January.

Understanding these patterns helps in comprehending global temperature distributions and the climatic influences of various geographical features.

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(a) Algeria and Morocco

(b) Botswana and Namibia

(c) Côte d’Ivoire and Ghana

(d) Madagascar and Mozambique

Explanation

The two largest cocoa producers in the world are Côte d’Ivoire and Ghana (c).

• (a) Algeria and Morocco: These countries are not known for significant cocoa production. Algeria and Morocco are not listed among the top cocoa-producing nations.
• (b) Botswana and Namibia: These countries do not have a notable presence in the cocoa production industry. They are not recognized as major cocoa producers.
• (c) Côte d’Ivoire and Ghana: These countries are the top two cocoa producers in the world, with Côte d’Ivoire leading and Ghana following closely.
• (d) Madagascar and Mozambique: While Madagascar produces high-quality cocoa, it contributes less than 1% to the global cocoa supply. Mozambique is not a significant cocoa producer.

Learn More

• Côte d’Ivoire:
  • Production: 2.2 million tonnes annually.
  • Global Share: 40.9% of the world’s cocoa.
  • Economic Impact: Cocoa contributes 15% to the country’s GDP and 40% to its export market.
  • Challenges: Significant deforestation due to cocoa farming.
• Ghana:
  • Production: 1.1 million tonnes annually.
  • Global Share: 20% of the world’s cocoa.
  • Economic Impact: Cocoa contributes 3.5% to the nation’s GDP and 25% to its export market.
  • Challenges: Biodiversity degradation and deforestation.
• Indonesia:
  • Production: Approximately 667,000 tonnes annually.
  • Global Share: 13% of the world’s cocoa.
  • Economic Impact: Cocoa contributes significantly to the nation’s GDP.
  • Challenges: Deforestation and soil degradation.
• Ecuador:
  • Production: Around 337,000 tonnes annually.
  • Global Share: 5% of the world’s cocoa.
  • Economic Impact: Cocoa contributes 0.5% to the GDP and 8% to exports.
  • Specialty: Known for high-grade single-origin chocolate.
• Brazil:
  • Production: Approximately 274,000 tonnes annually.
  • Global Share: 5% of the world’s cocoa.
  • Economic Impact: Cocoa farming is crucial for the economy but affects biodiversity.
• Cameroon:
  • Production: Around 300,000 tonnes annually.
  • Global Share: 5% of the world’s cocoa.
  • Economic Impact: Cocoa contributes 1.2% to the national GDP and 70% to exports.
• Nigeria:
  • Production: Approximately 280,000 tonnes annually.
  • Global Share: 5% of the world’s cocoa.
  • Economic Impact: Cocoa contributes 0.5% to the national GDP and 0.28% to exports.
• Peru:
  • Production: Around 171,000 tonnes annually.
  • Global Share: 3% of the world’s cocoa.
  • Economic Impact: Significant source of income for farmers.
  • Initiatives: Efforts to produce deforestation-free cocoa.
• Dominican Republic:
  • Production: Approximately 76,000 tonnes annually.
  • Global Share: Less than 2% of the world’s cocoa.
• Madagascar:
  • Production: Less than 1% of the world’s cocoa.
  • Specialty: Known for high-quality, fruity-flavored cocoa.

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(a) Ghaghara – Gomati – Gandak – Kosi

(b) Gomati Ghaghara – Gandak – Kosi

(c) Ghaghara Gomati – Kosi – Gandak

(d) Gomati Ghaghara – Kosi – Gandak

The correct sequence of the Himalayan rivers joining the Ganga downstream of Prayagraj from west to east is:(b) Gomati — Ghaghara — Gandak — Kosi

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• Gomati River:
  • Originates from Gomat Taal near Madho Tanda, Pilibhit.
  • It flows through Uttar Pradesh and joins the Ganga near Saidpur, Kaithi, close to Varanasi.
• Ghaghara River:
  • Originates from the northern slopes of the Himalayas in the Tibetan Plateau.
  • It is the largest tributary of the Ganges by volume and joins the Ganga at Chhapra, Bihar.
• Gandak River:
  • Originates from the Great Himalaya Range in Nepal.
  • It flows through Bihar and Uttar Pradesh and joins the Ganga near Patna at Sonpur.
• Kosi River:
  • Known as the Saptakoshi in Nepal due to its seven tributaries.
  • It flows through northern Bihar and joins the Ganga near Kursela in Katihar district.
  • Known for its shifting course and heavy flooding, earning the nickname “Sorrow of Bihar.”

These rivers are significant for their contributions to the Ganges’ flow and their impact on the regions they traverse, including their roles in agriculture, transportation, and cultural significance.

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Statement-I: Rainfall is one of the reasons for weathering of rocks.

Statement-II: Rain water contains carbon dioxide in solution.

Statement-III: Rain water contains atmospheric oxygen.

Which one of the following is correct in respect of the above statements?
(a) Both Statement-II and Statement-III are correct and both of them explain Statement-I
(b) Both Statement-II and Statement-III are correct, but only one of them explains Statement-I
(c) Only one of the Statements II and III is correct and that explains Statement-I
(d) Neither Statement-II nor Statement-III is correct

Correct Answer: (a) Both Statement-II and Statement-III are correct and both of them explain Statement-I

• Statement-I: Rainfall is one of the reasons for weathering of rocks.
  • This statement is true. Rainfall contributes to the weathering process through both physical and chemical means.
• Statement-II: Rain water contains carbon dioxide in solution.
  • This statement is true. Rainwater absorbs carbon dioxide from the atmosphere, forming a weak carbonic acid solution, which can chemically weather rocks.
• Statement-III: Rain water contains atmospheric oxygen.
  • This statement is true. Rainwater contains dissolved oxygen from the atmosphere, which can participate in oxidation processes that contribute to weathering.

Option Analysis:

• Option (a): Both Statement-II and Statement-III are correct and both of them explain Statement-I.
  • This option is correct. Both carbon dioxide and atmospheric oxygen in rainwater contribute to the chemical weathering of rocks.
• Option (b): Both Statement-II and Statement-III are correct, but only one of them explains Statement-I.
  • This option is incorrect. Both statements II and III are accurate and relevant to explaining weathering processes.
• Option (c): Only one of the Statements II and III is correct and that explains Statement-I.
  • This option is incorrect. Both statements are correct and contribute to the weathering process.
• Option (d): Neither Statement-II nor Statement-III is correct.
  • This option is incorrect. Both statements are accurate descriptions of the components of rainwater and their roles in weathering.

Learn More

• Weathering: The breaking down or dissolution of rocks and minerals on the Earth’s surface.
  • Types of Weathering:
    • Physical (Mechanical) Weathering:
      • Involves the breakdown of rocks and minerals by physical forces such as temperature changes, freeze-thaw cycles, and biological activity.
      • Example: Freeze-thaw action where water seeps into cracks, freezes, expands, and breaks the rock apart.
    • Chemical Weathering:
      • Involves the breakdown of rocks and minerals through chemical reactions, often involving water, acids, and gases.
      • Carbonation: Rainwater containing dissolved CO2 forms carbonic acid, which reacts with minerals like calcite in limestone, leading to dissolution.
      • Oxidation: Oxygen in rainwater reacts with minerals, particularly iron-bearing ones, to form oxides or rust, leading to weakening and breakdown.
      • Hydrolysis: Water reacts with minerals to form new minerals and soluble salts, altering the rock structure.
  • Factors Influencing Weathering:
    • Climate: Temperature and precipitation are critical; warm, wet climates enhance chemical weathering, while cold climates promote physical weathering.
    • Rock Type: Different minerals weather at different rates; for example, feldspar weathers faster than quartz.
    • Topography: Slope steepness affects the exposure of rocks to weathering agents.
    • Biological Activity: Plants, microbes, and animals contribute to both physical and chemical weathering through root growth, organic acids, and physical disturbances.
  • Importance of Weathering:
    • Soil Formation: Weathering is essential for breaking down rocks into smaller particles that mix with organic material to form soil.
    • Nutrient Cycling: Releases essential minerals and nutrients into the soil, making them available for plant uptake.
    • Landscape Shaping: Influences the formation of various landforms and contributes to the geological cycle.

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1. Finland

2. Germany

3. Norway

4. Russia

How many of the above countries have a border with the North Sea?

(a) Only one

(b) Only two

(c) Only three

(d) All four

The correct answer is (b) Only two.

• Finland: Does not have a border with the North Sea. Finland is bordered by the Baltic Sea, specifically the Gulf of Bothnia and the Gulf of Finland.
• Germany: Has a border with the North Sea. Germany’s coastline includes the North Sea and the Baltic Sea.
• Norway: Has a border with the North Sea. Norway’s coastline extends along the North Sea, the Norwegian Sea, and the Barents Sea.
• Russia: Does not have a border with the North Sea. Russia’s borders include the Baltic Sea, the Black Sea, and the Pacific Ocean, but not the North Sea.

Thus, only Germany and Norway have borders with the North Sea.

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North Sea

• Location: The North Sea is a shallow northeastern arm of the Atlantic Ocean, located between the British Isles and the mainland of northwestern Europe.
• Borders: It is bordered by Great Britain to the southwest and west, the Orkney and Shetland islands to the northwest, Norway to the northeast, Denmark to the east, Germany and the Netherlands to the southeast, and Belgium and France to the south.
• Connections: It connects to the Atlantic Ocean through the English Channel in the south and the Norwegian Sea in the north. It also connects to the Baltic Sea via the Skagerrak and Kattegat straits.
• Economic Importance: The North Sea is one of Europe’s most productive fisheries, a prominent shipping zone, and a source of petroleum and natural gas.
• Geopolitical Significance: Historically, the North Sea has been crucial for maritime trade and military strategy, influencing the rise of the Vikings, the Hanseatic League, and the British Empire.
• Environmental Issues: The North Sea faces environmental challenges such as overfishing, industrial and agricultural runoff, dredging, and dumping, leading to efforts to prevent degradation and safeguard economic benefits.

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Waterfall – Region – River

1. Dhuandhar – Malwa – Narmada

2. Hundru – Chota Nagpur – Subarnarekha

3. Gersoppa – Western Ghats – Netravati

In how many of the above rows is the given information correctly matched?

(a) Only one

(b) Only two

(c) All three

(d) None

The correct answer is (b) Only two.

• Dhuandhar Falls is located in the Malwa region and is formed by the Narmada River. This information is correctly matched.
• Hundru Falls is located in the Chota Nagpur Plateau and is formed by the Subarnarekha River. This information is also correctly matched.
• Gersoppa Falls (also known as Jog Falls) is located in the Western Ghats but is formed by the Sharavati River, not the Netravati River. This information is incorrectly matched.

Learn more

• Dhuandhar Falls:
  • Located in the Jabalpur district of Madhya Pradesh, India.
  • Formed by the Narmada River as it flows through the Marble Rocks and plunges down, creating a misty appearance.
  • The falls are approximately 30 meters high and are a popular tourist destination.
  • Features a cable car service for tourists to view the falls from different angles.
• Hundru Falls:
  • Located in the Ranchi district of Jharkhand, India.
  • Formed by the Subarnarekha River, falling from a height of 98 meters.
  • Known for its scenic beauty and rock formations created by erosion.
  • Popular as a picnic spot, especially during the dry season when the water flow is less intense.
• Gersoppa (Jog) Falls:
  • Located in the Uttara Kannada district of Karnataka, India.
  • Formed by the Sharavati River, with a drop of 253 meters, making it one of the highest waterfalls in India.
  • The falls consist of four distinct cascades: Raja, Rani, Roarer, and Rocket.
  • A major tourist attraction, especially during the monsoon season when the water flow is at its peak.

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In how many of the above rows is the given information correctly matched?

(a) Only one
(b) Only two
(c) Only three
(d) All four

Correct Answer: (b) Only two

Explanation:

• Row 1: Central Asia – Vosges – Fold mountain
  • Incorrect: The Vosges are block mountains, not fold mountains. They were formed by the uplift of bedrock plates due to a graben at the beginning of the Paleogene period.
• Row 2: Europe – Alps – Block mountain
  • Incorrect: The Alps are fold mountains, not block mountains. They were formed by the collision of the African and Eurasian tectonic plates, causing the folding and faulting of the Earth’s crust.
• Row 3: North America – Appalachians – Fold mountain
  • Correct: The Appalachians are fold mountains. They were formed by the collision of tectonic plates, which caused the folding and faulting of the Earth’s crust over millions of years.
• Row 4: South America – Andes – Fold mountain
  • Correct: The Andes are fold mountains. They were formed by the subduction of the Nazca Plate beneath the South American Plate, leading to the folding and faulting of the Earth’s crust.

Learn more:

Types of Mountains

• Fold Mountains:
  • Formed by the collision of tectonic plates, causing the Earth’s crust to fold and create mountain ranges.
  • Examples include the Himalayas, Rockies, Andes, and Appalachians.
  • Characterized by long, linear ranges with high peaks and deep valleys.
• Block Mountains:
  • Created when large areas of the Earth’s crust are broken and displaced vertically.
  • The uplifted blocks are called horsts, and the lowered blocks are called grabens.
  • Examples include the Vosges and the Black Forest in Europe.
  • Characterized by steep, flat-topped blocks separated by valleys or basins.
• Volcanic Mountains:
  • Formed by volcanic activity, where magma from the Earth’s mantle reaches the surface and solidifies.
  • Examples include Mount Fuji in Japan, Mount Kilimanjaro in Africa, and Mount St. Helens in the USA.
  • Characterized by conical shapes with craters at the summit.
• Dome Mountains:
  • Formed when magma pushes the crust upwards but does not erupt.
  • The overlying layers of rock are bent into a dome shape.
  • Examples include the Black Hills of South Dakota.
  • Characterized by rounded, dome-like shapes.
• Plateau Mountains:
  • Formed by erosion of an uplifted plateau.
  • The plateau is worn down by weathering and erosion, leaving behind mountain-like features.
  • Examples include the Colorado Plateau.
  • Characterized by flat-topped elevations with steep sides.

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