UPSC Prelims 2018
World Geography Previous Year Questions (PYQs)
Explore 4 solved UPSC Prelims 2018 World Geography questions with detailed step-by-step bilingual solutions, option analysis, and answer keys.
Consider the following statements:
- In India, State Governments do not have the power to auction non-coal mines.
- Andhra Pradesh and Jharkhand do not have gold mines.
- Rajasthan has iron ore mines.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 3 — 3 only
This question tests knowledge about mining regulations and mineral distribution in India. Among the three statements, only Statement 3 about Rajasthan having iron ore mines is correct.
❌ Statement 1 – Incorrect: State Governments have the power to auction non-coal mines under the Mines and Minerals (Development and Regulation) Amendment Act, 2015.
❌ Statement 2 – Incorrect: Both Andhra Pradesh (Anantapur district) and Jharkhand (several districts) have gold deposits and active mining operations.
✅ Statement 3 – Correct: Rajasthan has significant iron ore reserves, particularly in districts like Jaipur, Udaipur, and Jhunjhunu.
📝 Short Notes: Mineral Distribution in India
- Iron Ore: Major states include Odisha (largest producer), Chhattisgarh, Karnataka, Jharkhand, and Rajasthan. Rajasthan has deposits in Jaipur, Udaipur, Dausa, and Jhunjhunu districts.
- Gold: Found in Karnataka (Kolar Gold Fields, Hutti), Andhra Pradesh (Anantapur), Jharkhand (Singhbhum), Chhattisgarh, and Madhya Pradesh. Kolar Gold Fields were once among the deepest mines in the world.
- Mining Regulation: The MMDR Amendment Act 2015 empowered state governments to conduct auctions for mining leases of non-coal minerals through competitive bidding, replacing the earlier discretionary allocation system.
- Constitutional Provisions: Minerals are covered under Entry 23 of State List (Concurrent List after amendments), while regulation of mines and mineral development falls under Union List Entry 54.
- Major Mineral Producing States: Jharkhand (coal, iron ore, copper, mica), Odisha (iron ore, bauxite, chromite), Chhattisgarh (coal, iron ore, bauxite), Karnataka (iron ore, gold, manganese), Rajasthan (zinc, lead, marble, granite, sandstone, iron ore).
Consider the following statements:
- The Earth's magnetic field has reversed every few hundred thousand years.
- When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide.
- When living organisms originated, they modified the early atmosphere of the Earth.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 3 — 1 and 3 only
This question tests knowledge about Earth's magnetic field reversals and the evolution of Earth's atmosphere. Statements 1 and 3 are scientifically accurate, while Statement 2 contains factual errors about the early Earth's atmospheric composition.
✅ Statement 1 – Correct: The Earth's magnetic field undergoes geomagnetic reversals approximately every few hundred thousand years, a phenomenon recorded in volcanic rocks and ocean floor sediments.
❌ Statement 2 – Incorrect: The early Earth's atmosphere (over 4 billion years ago) had virtually no free oxygen and was dominated by carbon dioxide, water vapor, nitrogen, and methane—not 54% oxygen.
✅ Statement 3 – Correct: Living organisms, particularly cyanobacteria through photosynthesis during the Great Oxygenation Event (~2.4 billion years ago), fundamentally transformed Earth's atmosphere by adding oxygen.
📝 Short Notes: Earth's Atmospheric Evolution
- Primordial Atmosphere: Early Earth (4+ billion years ago) had no free oxygen; atmosphere consisted mainly of hydrogen, helium, water vapor, methane, ammonia, and carbon dioxide.
- Secondary Atmosphere: Formed through volcanic outgassing, releasing CO₂, nitrogen, water vapor, and sulfur compounds.
- Great Oxygenation Event (GOE): Around 2.4 billion years ago, cyanobacteria began photosynthesis, gradually increasing atmospheric oxygen from ~0% to ~21% today.
- Geomagnetic Reversals: Earth's magnetic poles switch positions irregularly; last reversal occurred ~780,000 years ago (Brunhes-Matuyama reversal).
- Evidence of Reversals: Preserved in magnetized minerals in volcanic rocks (paleomagnetism) and oceanic crust spreading from mid-ocean ridges.
- Impact on Life: The oxygen revolution caused mass extinction of anaerobic organisms but enabled evolution of complex aerobic life forms.
Among the following cities, which one lies on a longitude closest to that of Delhi?
Detailed Explanation:
Answer: Option 1 — Bengaluru
Delhi is located at approximately 77.10°E longitude, and among the given options, Bengaluru (77.59°E) lies closest to this longitude with a difference of only about 0.49°. Hyderabad (78.49°E), Nagpur (79.09°E), and Pune (73.86°E) are all farther away from Delhi's longitude.
📝 Short Notes: Longitudes of Major Indian Cities
| City | Longitude | Difference from Delhi |
|---|---|---|
| Delhi | 77.10°E | - |
| Bengaluru | 77.59°E | 0.49° |
| Hyderabad | 78.49°E | 1.39° |
| Nagpur | 79.09°E | 1.99° |
| Pune | 73.86°E | 3.24° |
- Bengaluru and Delhi nearly share the same longitudinal line, making them closest in east-west positioning.
- Pune lies significantly west of Delhi, while Hyderabad and Nagpur lie progressively east.
- Understanding longitude positions helps in determining time zones and relative geographical positioning of cities.
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Consider the following statements -
- Most of the world's coral reefs are in tropical waters.
- More than one-third of the world's coral reefs are located in the territories of Australia, Indonesia and the Philippines.
- Coral reefs host far more number of animal phyla than those hosted by tropical rainforests.
Which of the statements given above is/are correct?
Detailed Explanation:
Answer: Option 4 — 1, 2 and 3
All three statements about coral reefs are correct. Coral reefs are predominantly found in tropical waters where conditions are optimal for their growth. The distribution of coral reefs is highly concentrated, with Australia, Indonesia, and the Philippines together hosting more than one-third of the world's coral reefs. Remarkably, coral reefs exhibit exceptional biodiversity not just in terms of species numbers but also in phyletic diversity, hosting 32 out of 34 animal phyla compared to only 9 phyla in tropical rainforests.
✅ Statement 1 – Correct: Coral reefs primarily thrive in warm, shallow, clear tropical waters between 30°N and 30°S latitudes, where sea surface temperatures typically remain between 20°C and 30°C.
✅ Statement 2 – Correct: These three countries (Australia, Indonesia, and the Philippines) account for over 40% of the world's coral reef area, with Indonesia holding approximately 18%, Australia 17%, and the Philippines 9%.
✅ Statement 3 – Correct: While rainforests have a higher number of species, coral reefs have greater phyletic diversity, hosting 32 of the 34 recognized animal phyla compared to only about 9 phyla found in tropical rainforests.
📝 Short Notes: Coral Reefs
- Definition: Coral reefs are underwater structures made from calcium carbonate secreted by corals, which are marine invertebrates belonging to the class Anthozoa.
- Geographic Distribution: Found primarily in tropical and subtropical waters between 30°N and 30°S latitudes, covering less than 0.1% of the ocean floor but supporting 25% of marine species.
- Optimal Conditions: Require warm water (20-30°C), shallow depth (less than 50m for sunlight penetration), clear water with low turbidity, normal salinity (32-42 ppt), and minimal pollution.
- Major Coral Reef Regions: Great Barrier Reef (Australia - largest), Coral Triangle (Indonesia, Philippines, Malaysia, Papua New Guinea), Caribbean Sea, Red Sea, and Indian Ocean islands.
- Biodiversity Hotspots: Host 32 out of 34 animal phyla (highest phyletic diversity on Earth), support over 4,000 fish species, 800 coral species, and countless invertebrates.
- Ecological Importance: Provide coastal protection from waves and storms, support fisheries, generate tourism revenue, and are sources of medicinal compounds.
- Threats: Climate change and ocean warming (causing coral bleaching), ocean acidification, overfishing, pollution, destructive fishing practices, and coastal development.
UPSC Prelims 2018 - World Geography Chapter-wise Distribution
Fundamentals of Geography
2 Qs (50%)Oceanography
1 Qs (25%)Economic Geography
1 Qs (25%)UPSC Prelims 2018 - World Geography Questions FAQs
Q1 How many World Geography questions were asked in UPSC Prelims 2018?
Q2 What is the chapter-wise question distribution for World Geography in UPSC Prelims 2018?
- Fundamentals of Geography: 2 questions (50%)
- Oceanography: 1 questions (25%)
- Economic Geography: 1 questions (25%)