UPSC Prelims 2025 Analysis

Explanation

Statement I: Correct Without the atmosphere, Earth's surface would lose heat rapidly, especially at night, and the average temperature would be much lower than the freezing point of water. The Moon, which lacks an atmosphere, has extreme temperature variations, supporting this fact.

Statement II: Correct The atmosphere absorbs and traps heat (mainly through the greenhouse effect), which helps maintain Earth's average temperature at a level suitable for life. Without this effect, the planet would be much colder.

Statement III: Correct Certain gases in the atmosphere, such as carbon dioxide, methane, and water vapor, are very effective at absorbing and trapping infrared radiation. This is the basis of the greenhouse effect, which keeps Earth warm.

Therefore, all three statements are correct.

Explanation

Pair I: Arunachal Pradesh : The capital is named after a fort, and the State has two National Parks.

• Correct. The capital of Arunachal Pradesh is Itanagar, which is named after the historical Ita Fort ('Ita' means brick in Assamese). The state has two National Parks: Namdapha National Park and Mouling National Park.

Pair II: Nagaland : The State came into existence on the basis of the Thirteenth Constitutional Amendment Act.

• Correct. Nagaland became the 16th state of India on 1 December 1963. Its statehood was granted by the State of Nagaland Act, 1962, which was a Constitutional Amendment Act.

Pair III: Tripura : Initially a Part 'C' State, it became a centrally administered territory with the reorganization of States in 1956 and later attained the status of a full-fledged State.

• Correct. Tripura was a Part 'C' state after accession to India. In 1956, it became a Union Territory (centrally administered) under the States Reorganisation Act, and later, in 1972, it attained full statehood.

Therefore, all three pairs are correctly matched.

Explanation

Statement I: Correct The belt of ancient rocks from Brazil coast matches with those from Western Africa. This is one of the strongest pieces of geological evidence for continental drift. The rock formations, particularly the Precambrian cratons and fold belts on the eastern coast of South America align perfectly with those on the western coast of Africa when the continents are fitted together. The ages, rock types, and structural trends show remarkable continuity across the Atlantic Ocean.

Statement II: Correct The gold deposits of Ghana are indeed derived from the Brazil plateau when the two continents lay side by side. This is a well-documented example of mineral correlation evidence. The gold-bearing conglomerate beds and the geological structures containing gold deposits in Ghana have their direct counterparts in Brazil. The source rocks and geological processes that created these deposits were originally part of the same continental mass before the Atlantic Ocean opened.

Statement III: Correct The Gondwana system of sediments from India does have counterparts in six different landmasses of the Southern Hemisphere. The Gondwana sedimentary sequences found in India match remarkably well with similar formations in Antarctica, Australia, South Africa, South America, and Madagascar. These sediments contain similar fossil assemblages (like Glossopteris flora) and show similar depositional environments, indicating they were formed when these landmasses were joined together as the supercontinent Gondwanaland.

All three statements represent valid evidence for continental drift theory proposed by Alfred Wegener.

Explanation

I. Lake Tanganyika: Lake Tanganyika is located in Central Africa, specifically in the countries of Tanzania, Democratic Republic of the Congo, Burundi, and Zambia. Its approximate coordinates are 6°00′S 29°30′E. Given its location south of the equator, the equator does not pass through it.

II. Lake Tonlé Sap: Lake Tonlé Sap is located in Cambodia. Its approximate coordinates are 12°41′35″N 104°35′59″E. Given its location north of the equator, the equator does not pass through it.

III. Patos Lagoon: Patos Lagoon is located in the state of Rio Grande do Sul in southern Brazil. Its approximate coordinates are 31°30′S 51°30′W. Given its location south of the equator, the equator does not pass through it.

Therefore, the equator passes through none of these water bodies. Hence, Option D is correct.

Explanation

Statement I: This statement is correct. Scientific studies do indicate shifts in the Earth's rotation and axis. These shifts are small but measurable.

Statement II: This statement is also correct. Solar flares and coronal mass ejections (CMEs) do bombard the Earth's atmosphere with energy. However, these events primarily affect the outermost layers of the atmosphere (like the ionosphere and thermosphere) and have a minimal direct impact on the Earth's rotation or axis.

Statement III: This statement is also correct. As polar ice melts, the water redistributes towards the equator. This redistribution of mass affects the Earth's moment of inertia, which in turn influences the Earth's rotation. This is analogous to a spinning figure skater extending their arms outward, which slows their spin.

Considering how the statements relate:

Statement III directly explains Statement I, as the redistribution of mass due to melting ice impacts Earth's rotation. Statement II, while true, doesn't directly explain the changes in Earth's rotation and axis mentioned in Statement I. Solar flares primarily impact the atmosphere, not the planet's rotation. Statement III is the primary reason behind this effect.

Explanation

I. Botswana : Diamond — Correct Botswana is one of the world's leading producers of diamonds. The diamond industry is a major contributor to Botswana's economy.

II. Chile : Lithium — Correct Chile is among the top producers of lithium globally, with vast reserves in the Atacama Desert. It is a key player in the global lithium market.

III. Indonesia : Nickel — Correct Indonesia is the world's largest producer of nickel, a critical mineral for batteries and stainless steel production.

Therefore, all three pairs are correctly matched.

Explanation

I. Mallorca : Italy Mallorca is the largest island in the Balearic Islands, which are part of Spain, not Italy. Therefore, this pair is incorrectly matched.

II. Normandy : Spain Normandy is a region in northern France, famous for the D-Day landings during World War II. It is not in Spain. Therefore, this pair is incorrectly matched.

III. Sardinia : France Sardinia is the second-largest island in the Mediterranean Sea and is part of Italy, not France. Therefore, this pair is incorrectly matched.

Conclusion: None of the pairs are correctly matched.

Explanation

Statement I: Correct

• Anadyr (Russia) and Nome (Alaska, USA) are located on opposite sides of the International Date Line (IDL), but geographically they are relatively close (separated by the Bering Strait).
• Due to the IDL, there is a date difference of almost one day between them. When it is morning in Anadyr, it is still the previous day in Nome, even though the local time of day (morning) may be similar.

Statement II: Incorrect

• When it is Monday in Anadyr, it is still Sunday in Nome, not Tuesday. Anadyr is ahead of Nome by almost 21 hours (Anadyr is UTC+12, Nome is UTC-9).
• Therefore, Anadyr is almost a day ahead, not behind. So, when it is Monday in Anadyr, it is still Sunday in Nome, not Tuesday.

Explanation

Statement I: This is correct. Chalk is a very permeable rock because it allows water to pass through easily, while clay is considered quite impermeable or least permeable because it does not allow water to pass through easily.

Statement II: This is correct. Chalk is a porous rock, meaning it has many small holes or spaces that can absorb and hold water. This porosity is what makes chalk permeable.

Statement III: This is incorrect. Clay is not 'not at all porous'; it is actually made up of very fine particles and has tiny pores. However, the pores are so small that water cannot move through them easily, making clay impermeable, but not completely non-porous.

Conclusion: Only one of the Statements II and III is correct (Statement II), and it explains Statement I (why chalk is permeable).

Explanation

1. I. United Kingdom:

   • Mainland UK (England, Scotland, Wales, Northern Ireland) uses GMT (UTC+0) or BST (UTC+1).
   • However, the UK has numerous Overseas Territories, which significantly increase its number of time zones. Examples include:
     • Pitcairn Islands: UTC-8
     • Bermuda, Falkland Islands: UTC-3 (varies slightly for Falklands DST)
     • Cayman Islands, British Virgin Islands: UTC-4
     • Gibraltar: UTC+1/UTC+2 (same as Central European Time)
     • Akrotiri and Dhekelia (Cyprus): UTC+2/UTC+3
     • British Indian Ocean Territory: UTC+6
     • South Georgia and the South Sandwich Islands: UTC-2
   • In total, the UK spans 9 official time zones. This is more than four.

2. II. Denmark:

   • Mainland Denmark uses Central European Time (UTC+1 / UTC+2 during summer).
   • Greenland (an autonomous territory of Denmark) has multiple time zones:
     • West Greenland (most populated areas like Nuuk): UTC-3 (summer UTC-2)
     • East Greenland (e.g., Ittoqqortoormiit): UTC-1 (summer UTC+0)
     • Thule Air Base area: UTC-4
     • Danmarkshavn: UTC+0 (GMT, no DST)
   • Faroe Islands (another autonomous territory): UTC+0 / UTC+1 during summer.
   • Taking distinct base UTC offsets, Denmark has at least 5 (UTC+1, UTC+0, UTC-1, UTC-3, UTC-4). This is more than four.

3. III. New Zealand:

   • Mainland New Zealand: NZST (UTC+12) / NZDT (UTC+13).
   • Chatham Islands: CHAST (UTC+12:45) / CHADT (UTC+13:45).
   • Associated states/territories:
     • Tokelau: UTC+13.
     • Niue: UTC-11.
     • Cook Islands: UTC-10.
   • This gives 5 distinct time zones (UTC+12, UTC+12:45, UTC+13 (Tokelau being distinct from NZDT contextually), UTC-11, UTC-10). This is more than four.

4. IV. Australia:

   • Mainland Australia has three primary time zones:
     • Western Standard Time (AWST): UTC+8
     • Central Standard Time (ACST): UTC+9:30
     • Eastern Standard Time (AEST): UTC+10
     • Some of these observe daylight saving.
   • Offshore territories add more:
     • Lord Howe Island: UTC+10:30 / UTC+11
     • Norfolk Island: UTC+11 / UTC+12
     • Cocos (Keeling) Islands: UTC+6:30
     • Christmas Island: UTC+7
     • Australian Antarctic Territory: Has multiple stations with different time zones (e.g., Mawson UTC+5, Davis UTC+7, Casey UTC+8).
   • Australia has at least 8-9 official time zones. This is more than four.

5. V. Brazil:

   • Brazil officially uses four time zones:
     • Fernando de Noronha Time: UTC-2
     • Brasilia Time (official time, covers most populous regions): UTC-3
     • Amazon Time: UTC-4
     • Acre Time: UTC-5
   • Brazil has exactly four time zones. It does not have more than four.

Therefore, the United Kingdom, Denmark, New Zealand, and Australia have more than four time zones. Brazil has exactly four.

So, 4 of the listed countries have more than four time zones.

Explanation

Statement I: This statement is correct. In January (winter in the Northern Hemisphere), isotherms (lines of equal temperature) bend equatorward (towards the equator) while crossing landmasses because land cools down faster than water. Over the oceans, the isotherms bend poleward (towards the poles) because the sea retains heat and is warmer than the adjacent land at the same latitude.

Statement II: This statement is also correct. In January, due to the high specific heat of water, the air over the oceans remains warmer compared to the air over the landmasses in the Northern Hemisphere. Land loses heat quickly, making it colder than the oceans during winter.

Relationship between the statements: Statement II provides the reason for the pattern described in Statement I. The difference in temperature between land and ocean in January causes the isotherms to bend as described.

Conclusion: Both statements are correct, and Statement II explains Statement I.

Explanation

Statement I: This statement is correct. The amount of dust particles in the atmosphere is generally higher in subtropical and temperate regions compared to equatorial and polar regions. This is because:

• Subtropical and temperate areas often have dry conditions, sparse vegetation, and strong winds, which help lift dust into the atmosphere (e.g., Sahara Desert, Middle East, Central Asia).
• Equatorial regions are humid and have dense vegetation, which prevents dust from being easily lifted.
• Polar regions are covered with ice and snow, and have little exposed soil, so dust is minimal.

Statement II: This statement is incorrect. Subtropical and temperate areas actually have more dry winds, not less. For example, the trade winds and westerlies in these regions are often dry and strong, contributing to dust storms and the movement of dust particles. Dry winds are less common in equatorial regions (which are humid) and polar regions (which are cold and moist).

Conclusion: Statement I is correct, but Statement II is not correct.

Explanation

The correct answer is (C) Only four.

Let me analyze each country to determine which ones the Andes Mountains pass through:

Countries through which Andes pass:

• I. Bolivia: ✓ YES - The Andes run through western Bolivia, forming the Altiplano plateau
• II. Brazil: ✗ NO - Brazil is primarily located on the Brazilian Plateau and Amazon Basin; the Andes do not extend into Brazil
• III. Colombia: ✓ YES - The Andes split into three ranges (Cordillera Occidental, Central, and Oriental) in Colombia
• IV. Ecuador: ✓ YES - The Andes run north-south through Ecuador, dividing it into coastal, highland, and Amazon regions
• V. Paraguay: ✗ NO - Paraguay is entirely located in the interior lowlands of South America, east of the Andes
• VI. Venezuela: ✓ YES - The Venezuelan Andes (part of the Cordillera de Mérida) extend into western Venezuela

Key Geographic Facts:

• The Andes Mountains form the longest continental mountain range in the world, stretching along South America's western coast
• They extend through seven countries total: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, and Argentina
• From the given list, only Brazil and Paraguay do not have the Andes passing through them
• Brazil is separated from the Andes by other countries, while Paraguay lies in the interior plains

Therefore, option C is correct as exactly four of the listed countries have the Andes Mountains passing through them.