GN07 — World Geography

📖 GN07 · NDA General Ability Test — Geography ★ Moderate Yield — 2–3 Questions

World Geography tests your knowledge of Earth's major physical features, political divisions, and the strategic waterways that connect them. For NDA, the focus is on superlatives (largest, longest, deepest), important straits and canals, and key facts about continents and countries. This chapter rewards systematic memorisation — make a fact sheet of the key comparisons and review them daily.

🌎 NDA Focus: Nile = longest river; Amazon = largest by volume; Caspian Sea = largest lake; Pacific = largest and deepest ocean; Mariana Trench = deepest point; Sahara = largest hot desert; Antarctica = largest cold desert; Suez Canal = no locks (sea level); Panama Canal = has locks; Strait of Malacca = busiest strait.

PART 1 — CONTINENTS & OCEANS

1. World's Continents (Largest to Smallest)

Asia — Largest (44.6 million sq km); most populated; highest point: Everest (8,849 m); lowest point: Dead Sea (−430 m)
Africa — 2nd largest (30.3 million sq km); Sahara Desert; Nile River; 54 countries (most of any continent)
North America — 3rd largest; Rocky Mountains; Mississippi River system; Great Lakes; Panama is its southern limit
South America — 4th; Amazon Rainforest (world's largest tropical rainforest); Andes (world's longest mountain range above sea level); Angel Falls (world's highest waterfall)
Antarctica — 5th; no permanent human inhabitants; ice sheet; world's coldest, windiest, driest continent; highest average elevation
Europe — 6th; smallest continent by population density; Alps; Danube and Volga rivers
Australia — Smallest continent; world's largest island; Great Barrier Reef (east coast); Outback desert interior

2. World's Oceans (Largest to Smallest)

Pacific Ocean — Largest (~165 million sq km) AND deepest; Ring of Fire; Mariana Trench (deepest point on Earth); covers ~46% of world's water surface
Atlantic Ocean — 2nd largest; S-shaped; Mid-Atlantic Ridge; Gulf Stream; Bermuda Triangle; Columbus crossed this ocean
Indian Ocean — 3rd largest; named after India; monsoon-driven currents; warmest ocean; surrounded by Asia, Africa, Australia
Southern Ocean (Antarctic Ocean) — 4th; surrounds Antarctica; recognised by IHO in 2000; roughest seas
Arctic Ocean — Smallest and shallowest; mostly frozen; North Pole located here; surrounded by North America, Europe, Asia

PART 2 — WORLD SUPERLATIVES

3. Major Rivers, Lakes and Waterfalls

🌊 Major Rivers

Nile (Africa) — Longest river (6,650 km); Egypt; flows north into Mediterranean; Aswan Dam
Amazon (S. America) — Largest by volume; widest river; world's largest drainage basin; world's largest tropical rainforest
Yangtze (China) — Longest in Asia; Three Gorges Dam (world's largest hydroelectric dam)
Mississippi-Missouri (USA) — Longest in North America; drains into Gulf of Mexico
Congo (Zaire) (Africa) — 2nd largest by volume; world's deepest river; equatorial rainforest
Volga (Russia) — Longest in Europe; drains into Caspian Sea (not an ocean!)

📅 Major Lakes & Waterfalls

Caspian Sea — World's largest lake (saltwater); between Russia, Kazakhstan, Azerbaijan, Iran, Turkmenistan
Lake Superior — World's largest freshwater lake by surface area (Great Lakes, USA/Canada)
Lake Baikal — World's deepest lake (1,642 m) AND oldest; Russia; contains 20% of world's surface freshwater
Lake Victoria — Largest lake in Africa; source of White Nile; Uganda, Kenya, Tanzania
Angel Falls (Venezuela) — World's highest waterfall (979 m); Guiana Highlands
Niagara Falls (USA/Canada) — Not highest but most voluminous in N. America; tourist landmark
Victoria Falls (Zimbabwe/Zambia) — World's largest sheet of falling water; Zambezi River

4. World's Major Deserts

Desert	Location	Type	Key Fact
Sahara	North Africa (Algeria, Libya, Egypt, Mali, Niger, Chad, Sudan)	Hot — largest hot desert	Largest hot desert in world (~9.2 million sq km); Tuareg people; Nile flows through it
Gobi	Mongolia and NE China	Cold — largest cold desert	Largest cold desert; Bactrian camel habitat; part of Silk Road
Arabian	Arabian Peninsula	Hot	Second largest hot desert; contains Rub al Khali (Empty Quarter) — world's largest continuous sand desert
Atacama	Pacific coast of South America (Chile, Peru)	Coastal cold desert — driest non-polar desert	Driest non-polar desert on Earth; some areas have never recorded rainfall; cold Humboldt current causes aridity
Antarctic	Antarctica	Cold (ice desert)	Largest cold desert (~14 million sq km); technically the largest desert of any type on Earth
Thar	Rajasthan (India) and Pakistan	Hot	Only major desert in South Asia; Luni River is its only river; Indira Gandhi Canal (Rajasthan Canal) provides water
Kalahari	Botswana, Namibia, South Africa	Semi-arid (not true desert)	Not completely arid; San (Bushmen) people; Okavango Delta is nearby

PART 3 — STRAITS, CANALS & KEY FACTS

5. Important Straits and Canals

Strait/Canal	Location	Connects	Key Fact
Strait of Malacca	Between Malaysia/Singapore and Indonesia (Sumatra)	Indian Ocean (Andaman Sea) to Pacific Ocean (South China Sea)	World's busiest strait; 25% of world trade passes through; strategic chokepoint
Palk Strait	Between India and Sri Lanka	Palk Bay (Bay of Bengal) to Gulf of Mannar (Indian Ocean)	Adam's Bridge (Ram Setu) — chain of limestone shoals; ~55 km wide
Bering Strait	Between Russia (Siberia) and USA (Alaska)	Arctic Ocean to Pacific Ocean (Bering Sea)	Separates Asia from North America; narrowest point ~85 km; used by land bridge during Ice Age (migration of humans to Americas)
Strait of Gibraltar	Between Spain/Morocco	Atlantic Ocean to Mediterranean Sea	Only connection between Atlantic and Mediterranean; strategic for Europe; 14 km wide at narrowest
Strait of Hormuz	Between Iran and Oman	Persian Gulf to Gulf of Oman (Arabian Sea)	20% of world's oil passes through; most important oil transit chokepoint
Suez Canal	Egypt	Red Sea to Mediterranean Sea	~193 km long; no locks (sea level); opened 1869; avoids going around Africa; dramatically shortens Europe-Asia route
Panama Canal	Panama (Central America)	Pacific Ocean to Atlantic Ocean (Caribbean Sea)	~77 km; has locks; opened 1914; avoids going around South America; US controlled until 1999
Bosporus & Dardanelles	Turkey	Black Sea to Aegean Sea (Mediterranean)	Istanbul sits on Bosporus; critical for Russian naval access to Mediterranean; narrow (~0.7 km at Bosporus)

PART 4 — COUNTRIES, CAPITALS & KEY FACTS

6. Strategic Countries — NDA Focus

🇮🇳 India's Neighbours

Pakistan: Islamabad; shares longest land border with India (3,323 km); PoK dispute
China: Beijing; shares 3,488 km border (LAC); Aksai Chin and Arunachal Pradesh disputes
Nepal: Kathmandu; open border; Hindu kingdom; Mt Everest
Bhutan: Thimphu; only country that blocks internet; GDP = Gross National Happiness
Bangladesh: Dhaka; surrounded by India on 3 sides; shares Ganga-Brahmaputra delta; Sundarbans
Myanmar: Naypyidaw; India's gateway to SE Asia; shares Arakan coast
Sri Lanka: Sri Jayawardenepura Kotte; separated by Palk Strait; tea and rubber
Maldives: Malé; Indian Ocean; strategic location; tourism; coral islands; lowest-lying country

🌏 Global Key Facts

Largest country: Russia (17.1 million sq km); spans 11 time zones
Smallest country: Vatican City (0.44 sq km); within Rome, Italy
Most populated country: India (2023 onward overtook China)
Largest democracy: India
Highest capital: La Paz (Bolivia) at ~3,650 m
Equator crosses: Ecuador, Colombia, Brazil, Congo, Uganda, Kenya, Somalia, Maldives, Indonesia (13 countries)
BRICS nations: Brazil, Russia, India, China, South Africa (+ new members 2024)
G7 nations: USA, Canada, UK, France, Germany, Italy, Japan

📝 NDA PYQs — World Geography

Q1. The Suez Canal connects: NDA PYQ

(a) Atlantic Ocean to Pacific Ocean(b) Red Sea to Mediterranean Sea(c) Persian Gulf to Arabian Sea(d) Black Sea to Mediterranean Sea

✔ Answer: (b) Red Sea to Mediterranean Sea

The Suez Canal (193 km long; opened 1869; Egypt) connects the Red Sea to the Mediterranean Sea, dramatically shortening the shipping route between Europe and Asia by avoiding the long journey around Africa's Cape of Good Hope. Unlike the Panama Canal, the Suez Canal has NO LOCKS — it is a sea-level canal (the Red Sea and Mediterranean are at nearly the same level). The Panama Canal (Pacific to Atlantic) has locks because the two oceans are at different levels.

Q2. Which is the world's largest ocean? NDA PYQ

(a) Atlantic Ocean(b) Indian Ocean(c) Arctic Ocean(d) Pacific Ocean

✔ Answer: (d) Pacific Ocean

The Pacific Ocean is the largest (covers ~46% of Earth's water surface, ~165 million sq km) and deepest ocean (contains the Mariana Trench, Earth's deepest point at ~11,034 m). It is also the home of the Ring of Fire — the horseshoe-shaped zone of volcanic and seismic activity around its rim. The Pacific is larger than all of Earth's land area combined.

Q3. The Strait of Malacca is strategically important because: NDA PYQ

(a) It connects the Red Sea to the Mediterranean(b) About 25% of world trade (especially oil to East Asia) passes through it(c) It is the widest strait in the world(d) It separates India from Sri Lanka

✔ Answer: (b) 25% of world trade passes through it

The Strait of Malacca (between Malaysia/Singapore and Sumatra, Indonesia) is the world's busiest shipping lane. About 25% of global trade and 80% of China's oil imports pass through it. At its narrowest, it is only about 2.8 km wide. Its strategic importance makes it a critical geopolitical chokepoint — control of this strait is central to Asian maritime security. NDA tests both its location and significance.

🧠 Quick Memory Chart — GN07

🌎 World Records

Largest hot desert: Sahara (Africa)
Largest cold desert: Antarctica
Longest river: Nile (6,650 km)
Largest by volume: Amazon
Deepest lake: Baikal (1,642 m, Russia)

⚓ Oceans & Straits

Largest ocean: Pacific (also deepest)
Smallest ocean: Arctic
Suez: no locks; Red Sea ↔ Mediterranean
Panama: has locks; Pacific ↔ Atlantic
Malacca: busiest strait; 25% world trade

🇮🇳 Countries

Largest country: Russia
Smallest: Vatican City
Most populated: India (2023+)
India-Pakistan border: 3,323 km (longest)
Palk Strait: India ↔ Sri Lanka

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