UPSC Prelims 2025 Analysis

Explanation

✅ Statement I: Correct Without an atmosphere, Earth’s surface would lose heat rapidly and become much colder, like the Moon.

✅ Statement II: Correct The atmosphere traps heat via the greenhouse effect, maintaining a temperature suitable for life.

✅ Statement III: Correct Gases like CO₂, methane, and water vapor absorb infrared radiation, causing the greenhouse effect.

Correct Answer: All three statements are correct.

Explanation

This question tests knowledge of historical and administrative facts about northeastern Indian states.

✅ Pair I: Arunachal Pradesh – Correct

• Itanagar, the capital, is named after Ita Fort.
• The state has two National Parks: Namdapha and Mouling.

✅ Pair II: Nagaland – Correct

• Nagaland attained statehood via a constitutional amendment and came into being on 1 December 1963 through the State of Nagaland Act, 1962.

✅ Pair III: Tripura – Correct

• Tripura was a Part 'C' state, became a Union Territory in 1956, and was granted statehood in 1972.

Explanation

✅ Statement I: Correct Ancient rock belts on Brazil’s coast match those on Western Africa, showing geological continuity.

✅ Statement II: Correct Gold deposits in Ghana correlate with those on the Brazil plateau, indicating a shared origin.

✅ Statement III: Correct Gondwana sediments in India match those in Antarctica, Australia, South Africa, South America, and Madagascar, with similar fossils and environments.

Correct Answer: All three statements are correct.

Explanation

❌ Statement I: Incorrect Lake Tanganyika lies south of the Equator, in Tanzania, DRC, Burundi, and Zambia.

❌ Statement II: Incorrect Lake Tonlé Sap is in Cambodia, well north of the Equator.

❌ Statement III: Incorrect Patos Lagoon is in southern Brazil, far south of the Equator.

Correct Answer: (D) None The Equator does not pass through any of the three water bodies listed.

Explanation

Earth’s rotation and axis can shift due to changes in how mass is distributed across the planet, such as melting polar ice.

✅Statement I is correct:

• Studies show that Earth’s rotation and axis are shifting slightly due to internal mass redistribution.

✅ Statement II is correct:

• But it doesn’t explain the shift — solar flares affect only the upper atmosphere, not Earth’s rotation.

✅ Statement III is correct:

• It explains the shift — melting polar ice moves water toward the equator, altering Earth’s mass distribution and spin.

Explanation

This question checks knowledge of countries known for major natural resources that play key roles in global markets.

✅ I. Botswana : Diamond – Correct

• Botswana is a top global producer of diamonds, vital to its economy.

✅ II. Chile : Lithium – Correct

• Chile has vast lithium reserves in the Atacama Desert and is a leading global supplier.

✅ III. Indonesia : Nickel – Correct

• Indonesia is the world’s largest producer of nickel, crucial for batteries and steel.

Explanation

The question tests knowledge of European geography, particularly the correct country associations of famous regions.

❌ I. Mallorca : Italy

• Mallorca is part of Spain, not Italy.

❌ II. Normandy : Spain

• Normandy is a region in France, not Spain.

❌ III. Sardinia : France

• Sardinia belongs to Italy, not France.

Explanation

Anadyr (Russia) and Nome (Alaska, USA) lie close to each other geographically but are separated by the International Date Line, leading to a significant difference in calendar dates despite similar times of day.

✅ Statement I: Correct Due to the International Date Line, Anadyr and Nome can have the same time of day but different dates.

❌ Statement II: Incorrect When it’s Monday in Anadyr, it is still Sunday in Nome, not Tuesday—Anadyr is ahead of Nome by almost 21 hours.

Explanation

✅ Statement I: Correct Chalk is permeable (water passes easily); clay is impermeable (water passes poorly).

✅ Statement II: Correct Chalk is porous, with many small holes that hold water, making it permeable.

❌ Statement III: Incorrect Clay is porous but with very tiny pores that restrict water flow; it is impermeable but not non-porous.

Correct Answer: Only Statements I and II are correct; Statement II explains Statement I.

Explanation

Based on the distribution of official time zones including overseas territories, we can determine:

✅ United Kingdom – More than four (Total 9 Time Zones) ✅ Denmark – More than four (At least 5 Time Zones) ✅ New Zealand – More than four (Total 5 Time Zones) ✅ Australia – More than four (Total 8-9 Time Zones) ❌ Brazil – Exactly four

Therefore, four out of the five countries have more than four time zones.

Explanation

✅ Statement I: Correct In January, isotherms bend equatorward over land (which cools faster) and poleward over oceans (which retain heat).

✅ Statement II: Correct Oceans stay warmer than land in January because water has a higher specific heat.

✅ Relationship: Statement II explains why the isotherms behave as described in Statement I.

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

Explanation

✅ Statement I: Correct Subtropical and temperate regions have more dust due to dry conditions, sparse vegetation, and strong winds.

❌ Statement II: Incorrect Subtropical and temperate regions have more dry winds, not less, which help lift dust.

Correct Answer: Only Statement I is correct.

Explanation

✅ Statement I: Correct Andes pass through Bolivia, forming the Altiplano plateau.

❌ Statement II: Incorrect Andes do not pass through Brazil, which lies on the Brazilian Plateau.

✅ Statement III: Correct Andes pass through Colombia, where they split into three mountain chains.

✅ Statement IV: Correct Andes run north-south through Ecuador, shaping its geography.

❌ Statement V: Incorrect Paraguay lies in the interior lowlands; Andes do not pass through it.

✅ Statement VI: Correct The Venezuelan Andes extend into western Venezuela (Cordillera de Mérida).

Correct Answer: (C) Only four ✅ Andes pass through: Bolivia, Colombia, Ecuador, Venezuela ❌ Not through: Brazil, Paraguay