Physics — Mechanics, Heat, Thermodynamics & Electricity

Why This Chapter Matters

World geography questions in RRB ALP and Technician papers usually target the same handful of facts every cycle: continents and their basic stats, countries and capitals, and famous landmarks. It's a compact, high-return topic, typically worth 2 to 4 marks, and unlike Indian geography, you don't need dozens of state-level details, just a well-organised world map in your head. That makes this one of the fastest chapters in the whole book to convert into guaranteed marks.

The biggest mistake aspirants make with world geography is trying to memorise a long, unordered country-capital list and hoping it sticks. It rarely does under exam pressure, because there's no structure to hang the facts on. This chapter instead builds the world region by region, continent by continent, so each capital or landmark sits inside a mental "folder" you can open quickly, rather than floating loose in a pile you have to search through fact by fact.

1. The Seven Continents

Earth's land is divided into seven continents, and knowing their basic stats cold is worth more than any single country fact, because comparison questions ("largest continent," "smallest by population," and similar) appear constantly.

Continent	Approx. Rank by Area	Key Identifying Fact
Asia	1st, largest	Home to over half the world's population; includes India, China
Africa	2nd	Contains the Sahara, the world's largest hot desert
North America	3rd	Includes USA, Canada, Mexico
South America	4th	Contains the Amazon rainforest and river
Antarctica	5th	Covered almost entirely in ice; no permanent population
Europe	6th	Smallest continent aside from Australia; densely populated
Australia (Oceania)	7th, smallest	Smallest continent; also a single country

Exam trap: Australia is both a continent and a country, the only landmass with that dual identity. Questions sometimes test whether students know Australia the continent is often referred to more broadly as "Oceania" when including nearby island nations like New Zealand and Papua New Guinea.

Memory hook: "A Aunt Never Sat Alone Eating Apples" gives you the first letters in one workable order: Asia, Africa, North America, South America, Antarctica, Europe, Australia. Read it as a sentence a few times and the continent order sticks faster than a bare list.

1.1 Continents by Population

Asia holds well over half of the world's population, largely due to India and China alone. Africa ranks second by population and has the fastest-growing population of any continent currently. Antarctica has no permanent residents; only rotating scientific research staff live there temporarily.

2. Asia: The Largest Continent

Asia is home to 48 recognised countries and stretches from the Arctic Circle in Russia's north down to the equator in Indonesia.

Country	Capital	Notable Fact
China	Beijing	Most populous country for decades, now second to India
Japan	Tokyo	Island nation, highly developed economy
Russia	Moscow	Largest country in the world by area, spans Europe and Asia
Nepal	Kathmandu	Home to Mount Everest, world's tallest peak
Sri Lanka	Sri Jayawardenepura Kotte (administrative), Colombo (commercial)	Island nation south of India
Bangladesh	Dhaka	Shares a long border with India
Pakistan	Islamabad	Borders India to the northwest
Saudi Arabia	Riyadh	Home to Mecca and Medina, Islam's holiest cities
Indonesia	Jakarta	Largest archipelago nation, most populous Muslim-majority country
South Korea	Seoul	Major East Asian economy

Exam trap: Sri Lanka has two capital-related facts that regularly get confused: Sri Jayawardenepura Kotte is the official administrative capital, while Colombo remains the commercial capital and the city most people think of by default. Papers occasionally test this split directly.

Russia deserves a special mention here: it's the largest country in the world by area, and its landmass is so vast that it spans both Europe and Asia, straddling 11 time zones, more than any other country.

3. Africa: The Continent of Deserts and Rivers

Africa has 54 recognised countries, the most of any continent, and is home to the world's longest river and largest hot desert.

Country	Capital	Notable Fact
Egypt	Cairo	Home to the Nile, the world's longest river, and the Giza Pyramids
South Africa	Pretoria (administrative), Cape Town (legislative), Bloemfontein (judicial)	Only country with three capital cities
Nigeria	Abuja	Africa's most populous country
Kenya	Nairobi	Known for the Great Rift Valley and wildlife safaris
Ethiopia	Addis Ahaba	One of the few African nations never fully colonised
Morocco	Rabat	North African nation bordering the Sahara
Tanzania	Dodoma	Home to Mount Kilimanjaro, Africa's tallest peak

Exam trap: South Africa's three-capital system (administrative, legislative, judicial) is one of the most tested single facts about the country. Most students only remember one capital, usually Pretoria, and miss the other two when a question asks specifically about the legislative or judicial seat.

The Nile River, at roughly 6,650 km, is the world's longest river, flowing north through northeastern Africa into the Mediterranean Sea. The Sahara Desert, covering most of North Africa, is the world's largest hot desert, though the Antarctic Desert (a cold desert) is actually larger overall; deserts are defined by low precipitation, not by heat.

Exam trap: The "world's largest desert" is technically Antarctica, since deserts are classified by rainfall, not temperature. The Sahara is only the largest hot desert. This distinction is a favourite exam curveball.

4. Europe: Small Continent, Dense History

Europe has 44 recognised countries packed into a relatively small area, making it the second-smallest continent, just ahead of Australia.

Country	Capital	Notable Fact
United Kingdom	London	Includes England, Scotland, Wales, Northern Ireland
France	Paris	Home to the Eiffel Tower
Germany	Berlin	Largest economy in Europe
Italy	Rome	Home to the Vatican City, the world's smallest country
Spain	Madrid	Shares the Iberian Peninsula with Portugal
Russia (partly in Europe)	Moscow	Straddles Europe and Asia
Switzerland	Bern	Known for permanent neutrality in global conflicts
Greece	Athens	Considered the birthplace of democracy
Netherlands	Amsterdam	Known for extensive land reclaimed from the sea

Exam trap: Switzerland's capital is Bern, not Zurich or Geneva. Zurich is the largest and most well-known city, and Geneva hosts many international organisations, but neither is the capital. This mismatch between "most famous city" and "actual capital" trips up a large share of students, and the same trap applies to several other countries too, so always double-check capital claims against fame.

Vatican City, located entirely within Rome, Italy, is the world's smallest independent country by both area and population, and is the spiritual centre of the Roman Catholic Church, headed by the Pope.

5. North America: From the Arctic to the Tropics

North America contains 23 recognised countries, though most exam questions focus heavily on just three: the USA, Canada, and Mexico.

Country	Capital	Notable Fact
United States	Washington, D.C.	World's largest economy
Canada	Ottawa	World's second-largest country by area
Mexico	Mexico City	Bridges North and Central America
Cuba	Havana	Largest island nation in the Caribbean
Jamaica	Kingston	Caribbean island nation

Exam trap: New York is often wrongly assumed to be the capital of the United States because of its size and fame. The actual capital is Washington, D.C., a purpose-built federal district that isn't part of any state.

Canada, at roughly 9.98 million square km, is the world's second-largest country by area after Russia, though its population is small relative to its size, since much of its northern territory lies in the Arctic and is sparsely inhabited.

6. South America: The Continent of the Amazon

South America has 12 recognised countries, dominated geographically by the Amazon rainforest and the Andes mountain range, the world's longest continental mountain range.

Country	Capital	Notable Fact
Brazil	Brasília	Largest country in South America; most of the Amazon lies here
Argentina	Buenos Aires	Second-largest country in South America
Peru	Lima	Home to the ancient Incan site of Machu Picchu
Chile	Santiago	Extremely long, narrow country along the Pacific coast
Colombia	Bogotá	Only South American country with coastlines on both Pacific and Caribbean
Venezuela	Caracas	Home to Angel Falls, the world's tallest waterfall

Exam trap: Brazil's capital is Brasília, a planned city built specifically to serve as capital in 1960, not Rio de Janeiro or São Paulo, which are far more famous internationally but are not the seat of government. This is one of the most commonly missed capital facts in the entire syllabus, so lock it in firmly.

The Amazon River, while slightly shorter than the Nile in most measurements, carries by far the largest volume of water of any river on Earth, roughly a fifth of all the world's river water discharge, and the Amazon Rainforest surrounding it is often called the "lungs of the Earth" for the vast amount of oxygen it produces and carbon dioxide it absorbs.

7. Oceania and Antarctica

Oceania includes Australia along with numerous Pacific island nations: New Zealand, Papua New Guinea, Fiji, and smaller island states.

Country	Capital	Notable Fact
Australia	Canberra	Both a country and a continent
New Zealand	Wellington	Known for the Southern Alps and unique wildlife
Papua New Guinea	Port Moresby	One of the most linguistically diverse countries on Earth
Fiji	Suva	Pacific island nation

Exam trap: Australia's capital is Canberra, not Sydney. Sydney is the largest and most internationally recognised city, home to the Sydney Opera House, but it isn't the seat of government. This is the same "famous city versus actual capital" trap that appears with Brazil and South Africa.

Antarctica is the only continent with no native population and no permanent country. It is governed collectively under the Antarctic Treaty System, signed in 1959, which sets it aside for peaceful scientific research and prohibits military activity and mineral resource extraction for commercial purposes. Multiple countries maintain research stations there, but no nation holds full sovereign control.

8. Major World Landmarks

A short, well-chosen list of physical and built landmarks covers most of what exams actually test.

• Mount Everest (8,849 m), on the Nepal-China border, is the world's tallest mountain above sea level.
• Mariana Trench, in the western Pacific Ocean, is the deepest known point in Earth's oceans, reaching nearly 11,000 metres below sea level.
• Sahara Desert, spanning North Africa, is the world's largest hot desert.
• Nile River (Africa) is the world's longest river; the Amazon River (South America) carries the greatest volume of water.
• Angel Falls, in Venezuela, is the world's tallest uninterrupted waterfall, at roughly 979 metres.
• Lake Baikal, in Russia, is the world's deepest freshwater lake and holds the largest volume of fresh water of any lake on Earth.
• Caspian Sea, bordered by Russia, Kazakhstan, and Iran among others, is the world's largest inland body of water, technically classified as the world's largest lake despite its name.
• Great Barrier Reef, off Australia's northeast coast, is the world's largest coral reef system, visible even from space.
• Sahara, Gobi, Kalahari are three of the most exam-referenced deserts: Sahara (North Africa, hot), Gobi (Mongolia/China, cold desert), and Kalahari (Southern Africa, semi-arid).

Exam trap: The Caspian Sea is called a "sea" by name but is functionally the world's largest lake, since it's fully enclosed by land with no ocean outlet. Do not let the name "sea" mislead you into excluding it from lake-related questions.

Analogy: Think of the world's water superlatives like a family with three different specialities: the Nile is the marathon runner (longest distance), the Amazon is the heavy lifter (largest volume carried), and the Caspian Sea is the odd cousin who got the name "sea" but actually belongs in the "lake" family reunion.

9. Time Zones and the International Date Line

The world is divided into roughly 24 time zones, each generally spanning about 15 degrees of longitude, based on Earth completing one full rotation (360 degrees) every 24 hours. Time zones are measured relative to UTC (Coordinated Universal Time), the modern successor to GMT (Greenwich Mean Time) as the global reference standard.

The International Date Line runs roughly along the 180-degree meridian through the Pacific Ocean, zig-zagging around some island territories to avoid splitting countries across two calendar dates. Crossing it going east subtracts a day; crossing it going west adds a day. This is why, in practical terms, countries just west of the line, like New Zealand and Fiji, are among the first in the world to welcome a new calendar day, while places just east of it, in the mid-Pacific, are among the last.

Memory hook: "West gains a day, East loses a day, when crossing the line where dates trade places." Repeating this simple line a couple of times settles the direction confusion that trips up most students on date-line questions.

10. Straits, Canals, and Choke Points

A handful of narrow water passages appear again and again in world geography questions because they carry outsized importance for global shipping and trade, far beyond their small size on a map.

The Strait of Gibraltar connects the Atlantic Ocean to the Mediterranean Sea and separates Spain from Morocco, marking the narrowest gap between Europe and Africa. The Strait of Malacca, between Malaysia/Indonesia and the island of Sumatra, is one of the busiest shipping lanes on Earth, carrying a huge share of trade moving between the Indian Ocean and the Pacific Ocean, including most of the oil shipped from the Middle East to East Asia. The Bering Strait separates Russia and Alaska (USA), marking the narrowest gap between Asia and North America, and is often cited as the likely route by which early humans migrated from Asia into the Americas thousands of years ago.

Two artificial canals matter just as much as natural straits. The Suez Canal, cut through Egypt, connects the Mediterranean Sea to the Red Sea, letting ships travel between Europe and Asia without sailing all the way around Africa; a single blockage here in 2021 disrupted global shipping for days and made headlines worldwide, a good reminder of how much of world trade depends on a handful of narrow passages. The Panama Canal, cut through Panama in Central America, connects the Atlantic and Pacific Oceans, sparing ships the long detour around South America's southern tip.

Analogy: Think of these straits and canals as toll gates on a busy highway. The highway (the ocean) is wide open everywhere else, but ships funnel through these narrow gates because going around costs enormous time and fuel, exactly like taking a shortcut through a single mountain pass instead of driving around the whole range.

Exam trap: Do not confuse the Suez Canal (Mediterranean to Red Sea, cutting across Egypt) with the Panama Canal (Atlantic to Pacific, cutting across Central America). Both are famous man-made shortcuts, but they sit on opposite sides of the globe and connect entirely different oceans.

Quick Revision — One-Line Facts

• Earth has seven continents: Asia, Africa, North America, South America, Antarctica, Europe, and Australia (Oceania).
• Asia is the largest continent by both area and population.
• Australia is the smallest continent and is also a single country.
• Russia is the largest country in the world by area, spanning both Europe and Asia across 11 time zones.
• Canada is the world's second-largest country by area, after Russia.
• China's capital is Beijing; Japan's capital is Tokyo.
• Nepal is home to Mount Everest, the world's tallest peak, on its border with China (Tibet).
• Sri Lanka's administrative capital is Sri Jayawardenepura Kotte, while Colombo remains its commercial capital.
• Africa has 54 countries, the most of any continent.
• South Africa uniquely has three capitals: Pretoria (administrative), Cape Town (legislative), and Bloemfontein (judicial).
• Egypt is home to the Nile, the world's longest river, and the Giza Pyramids.
• The Sahara is the world's largest hot desert; Antarctica is technically the world's largest desert overall by low precipitation.
• Switzerland's capital is Bern, not the more famous cities of Zurich or Geneva.
• Vatican City, within Rome, is the world's smallest independent country.
• Greece is widely considered the birthplace of democracy.
• The capital of the United States is Washington, D.C., not New York.
• Brazil's capital is Brasília, a planned city, not Rio de Janeiro or São Paulo.
• The Amazon River carries the greatest volume of water of any river on Earth.
• The Andes, running through South America, form the world's longest continental mountain range.
• Angel Falls in Venezuela is the world's tallest uninterrupted waterfall.
• Australia's capital is Canberra, not Sydney.
• Antarctica has no permanent population and is governed under the Antarctic Treaty System since 1959.
• The Mariana Trench in the Pacific Ocean is the deepest known point in the world's oceans.
• Lake Baikal in Russia is the world's deepest freshwater lake by volume.
• The Caspian Sea is technically the world's largest lake despite carrying the word "sea" in its name.
• The Great Barrier Reef, off Australia's coast, is the world's largest coral reef system.
• The world is divided into roughly 24 time zones, each about 15 degrees of longitude wide.
• The International Date Line runs close to the 180-degree meridian through the Pacific Ocean.
• Crossing the International Date Line eastward subtracts a calendar day; crossing westward adds one.
• Saudi Arabia's capital, Riyadh, is home to two of Islam's holiest cities, Mecca and Medina, elsewhere in the country.

Memory Tables

Table 1: Continents Ranked by Area (Largest to Smallest)

Rank	Continent	Key Fact
1	Asia	Most populous continent
2	Africa	Most countries (54)
3	North America	Includes USA, Canada, Mexico
4	South America	Home to the Amazon
5	Antarctica	No permanent population
6	Europe	Dense in countries, small in area
7	Australia (Oceania)	Smallest continent, also a country

Table 2: "Famous City vs Actual Capital" Trap List

Country	Famous City (NOT capital)	Actual Capital
United States	New York	Washington, D.C.
Brazil	Rio de Janeiro / São Paulo	Brasília
Australia	Sydney	Canberra
Switzerland	Zurich / Geneva	Bern
South Africa	Johannesburg	Pretoria / Cape Town / Bloemfontein

Table 3: World Superlatives

Superlative	Landmark	Location
Tallest mountain	Mount Everest	Nepal-China border
Longest river	Nile	Northeastern Africa
Largest river by volume	Amazon	South America
Deepest ocean point	Mariana Trench	Western Pacific Ocean
Largest hot desert	Sahara	North Africa
Tallest waterfall	Angel Falls	Venezuela
Largest coral reef system	Great Barrier Reef	Off northeast Australia
Smallest country	Vatican City	Within Rome, Italy

Practice MCQs

Q1. Which is the largest continent in the world by both area and population? (a) Africa (b) Asia (c) North America (d) Europe

Q2. Which country is the largest in the world by land area? (a) Canada (b) China (c) Russia (d) United States

Q3. South Africa is unique among nations for having: (a) Two official languages only (b) Three separate capital cities (c) No capital city (d) A capital shared with a neighbouring country

Q4. The Nile River, the world's longest river, flows through which continent? (a) Asia (b) South America (c) Africa (d) Australia

Q5. Which city is the actual capital of Switzerland, despite Zurich being more internationally famous? (a) Geneva (b) Zurich (c) Bern (d) Basel

Q6. What is the capital of Brazil? (a) Rio de Janeiro (b) São Paulo (c) Brasília (d) Salvador

Q7. Which river carries the greatest volume of water of any river in the world? (a) Nile (b) Amazon (c) Mississippi (d) Yangtze

Q8. The capital of the United States is: (a) New York (b) Washington, D.C. (c) Los Angeles (d) Chicago

Q9. What is the capital of Australia? (a) Sydney (b) Melbourne (c) Canberra (d) Perth

Q10. Which desert is generally described as the world's largest hot desert? (a) Gobi Desert (b) Kalahari Desert (c) Sahara Desert (d) Thar Desert

Q11. The Mariana Trench, the deepest known point in the world's oceans, is located in which ocean? (a) Atlantic Ocean (b) Indian Ocean (c) Pacific Ocean (d) Arctic Ocean

Q12. The Caspian Sea, despite its name, is technically classified as the world's: (a) Largest ocean (b) Largest lake (c) Deepest sea (d) Smallest gulf

Q13. Which continent has no permanent population and is governed under an international treaty focused on peaceful scientific research? (a) Africa (b) Australia (c) Antarctica (d) Europe

Q14. Vatican City, the world's smallest independent country, is located entirely within which city? (a) Milan (b) Rome (c) Venice (d) Florence

Q15. Crossing the International Date Line while travelling eastward causes a traveller to: (a) Gain a calendar day (b) Lose a calendar day (c) Experience no date change (d) Skip a time zone entirely

Answer Key

Q	Answer	One-line reason
1	(b) Asia	Asia leads every other continent in both total land area and total population.
2	(c) Russia	Russia's landmass spans both Europe and Asia, making it the largest country by area on Earth.
3	(b)	South Africa splits government functions across Pretoria, Cape Town, and Bloemfontein.
4	(c) Africa	The Nile flows north through northeastern Africa before reaching the Mediterranean Sea.
5	(c) Bern	Bern is Switzerland's actual seat of government, despite Zurich's larger size and global fame.
6	(c) Brasília	Brasília was purpose-built and designated as Brazil's capital in 1960.
7	(b) Amazon	The Amazon discharges far more water volume than any other river on Earth.
8	(b) Washington, D.C.	This purpose-built federal district, not New York, serves as the seat of the US government.
9	(c) Canberra	Canberra was chosen as a planned capital, distinct from the larger and more famous Sydney.
10	(c) Sahara Desert	The Sahara is the largest desert classified specifically as hot; Antarctica is larger overall by aridity.
11	(c) Pacific Ocean	The Mariana Trench lies in the western Pacific Ocean near the Mariana Islands.
12	(b) Largest lake	Being fully enclosed by land with no ocean outlet makes the Caspian Sea a lake by definition.
13	(c) Antarctica	The Antarctic Treaty System, since 1959, reserves the continent for peaceful research only.
14	(b) Rome	Vatican City sits as an independent enclave entirely within the city of Rome, Italy.
15	(b) Lose a calendar day	Travelling east across the date line moves a traveller back one calendar day.