Class 10 Social Science Geography Chapter 3 — Geography of the World
Welcome to HSLC Guru! This chapter takes you on a journey across the globe — from the shape and motions of the Earth to the continents, oceans, mountains, rivers, climates, populations and economies that shape our world. The notes follow the ASSEB Class 10 Social Science (Geography) syllabus and are designed for English-medium learners preparing for the HSLC examination.
Chapter Summary
The Earth is the third planet from the Sun and the only known planet that supports life. Its true shape is described as a geoid — slightly flattened at the poles and bulged at the equator due to rotation. The Earth has an equatorial diameter of about 12,756 km and a polar diameter of about 12,714 km. It performs two main motions: rotation on its axis once every 24 hours, which causes day and night, and revolution around the Sun once every 365.25 days, which causes the seasons. The extra quarter day is adjusted by adding one day to February every fourth year, called a leap year.
To locate places on the Earth, a network of latitudes (parallels) and longitudes (meridians) is used. The Equator (0°) is the main latitude, while the Prime Meridian (0°) passing through Greenwich is the main longitude. The International Date Line (IDL) roughly follows 180° longitude in the Pacific Ocean — crossing it eastward subtracts a day and crossing westward adds a day. India follows Indian Standard Time (IST) based on the 82°30’E meridian passing through Mirzapur (Uttar Pradesh), which is 5 hours 30 minutes ahead of GMT. The tilt of the Earth’s axis (23½°) along with revolution produces seasons; the equinoxes (21 March and 23 September) bring equal day and night, while the solstices (21 June and 22 December) mark the longest and shortest days.
The Earth’s surface is divided into seven continents — Asia, Africa, North America, South America, Antarctica, Europe and Australia — and five oceans — Pacific, Atlantic, Indian, Southern (Antarctic) and Arctic. Major mountain ranges include the Himalayas, Andes, Rockies, Alps and Atlas. Notable plateaus include the Tibetan Plateau (the “Roof of the World”), Deccan Plateau and East African Plateau, while extensive plains include the Indo-Gangetic Plain, Great Plains of North America and the European Plain. The world’s longest rivers — the Nile, Amazon, Yangtze, Mississippi, Ganga, Volga and Congo — have nourished great civilisations and continue to support agriculture, transport and hydroelectric power.
Major deserts include the Sahara (the largest hot desert), Gobi, Atacama, Kalahari and Thar. World climates are broadly classified as equatorial, tropical, monsoon, Mediterranean, temperate and polar. World population is unevenly distributed — densely populated in fertile river valleys and industrial regions, sparsely populated in deserts, dense forests and polar areas. Economic activities are organised into agricultural belts (wheat, rice, cotton), mineral belts and industrial regions (Ruhr, Great Lakes, Kanto). International trade flows through key routes — the Suez Canal, Panama Canal, Strait of Hormuz and Strait of Malacca. Global institutions like the UN, WTO and IMF coordinate cooperation, trade and finance, while issues such as climate change, pollution and inequality remain shared global concerns.
Textbook Questions and Answers
A. Very Short Answer Type Questions (1 Mark)
Q1. What is the true shape of the Earth called?
Answer: The true shape of the Earth is called a geoid — flattened at the poles and bulged at the equator.
Q2. How many continents and oceans are there on the Earth?
Answer: There are seven continents and five oceans on the Earth.
Q3. On which longitude is Indian Standard Time based?
Answer: Indian Standard Time is based on the 82°30’E meridian passing through Mirzapur, Uttar Pradesh.
Q4. Name the largest hot desert in the world.
Answer: The Sahara Desert in northern Africa is the largest hot desert in the world.
Q5. Which is the longest river in the world?
Answer: The Nile in Africa is generally regarded as the longest river in the world (about 6,650 km).
Q6. What does IDL stand for?
Answer: IDL stands for the International Date Line, which roughly follows the 180° meridian in the Pacific Ocean.
Q7. How long does the Earth take to complete one revolution around the Sun?
Answer: The Earth takes 365¼ days (365.25 days) to complete one revolution around the Sun.
Q8. Name two major canals used in international trade.
Answer: The Suez Canal (Egypt) and the Panama Canal (Central America) are two major canals used in international trade.
Q9. Which continent is known as the “frozen continent”?
Answer: Antarctica is known as the frozen continent because it is permanently covered with thick ice sheets.
Q10. What is the headquarters of the United Nations (UN)?
Answer: The headquarters of the United Nations is located in New York City, USA.
B. Short Answer Type Questions (2–3 Marks)
Q1. Differentiate between rotation and revolution of the Earth.
Answer: Rotation is the spinning of the Earth on its own axis once every 24 hours, which causes day and night. Revolution is the movement of the Earth around the Sun once every 365.25 days, which along with the axial tilt causes the change of seasons and variations in the length of day and night.
Q2. What are latitudes and longitudes? Why are they important?
Answer: Latitudes are imaginary horizontal lines (parallels) drawn east-west around the Earth, measured in degrees north or south of the Equator. Longitudes are imaginary vertical lines (meridians) drawn north-south, measured east or west of the Prime Meridian. Together they form a grid that helps locate any place on the Earth precisely and is the basis for calculating time zones.
Q3. Explain the equinoxes and solstices.
Answer: Equinoxes occur on 21 March (vernal) and 23 September (autumnal) when the Sun shines directly over the Equator and day and night are of equal length all over the world. Solstices occur on 21 June (summer solstice — longest day in the Northern Hemisphere) and 22 December (winter solstice — shortest day in the Northern Hemisphere). They are caused by the 23½° tilt of the Earth’s axis combined with revolution.
Q4. Name the seven continents and five oceans of the world.
Answer: The seven continents are: Asia, Africa, North America, South America, Antarctica, Europe and Australia. The five oceans are: Pacific, Atlantic, Indian, Southern (Antarctic) and Arctic oceans. The Pacific is the largest ocean and Asia is the largest continent.
Q5. Why is the Strait of Malacca important in international trade?
Answer: The Strait of Malacca, located between the Malay Peninsula and the Indonesian island of Sumatra, is the shortest sea route between the Indian Ocean and the Pacific Ocean. It carries a huge volume of trade between West Asia, South Asia, Southeast Asia, China, Japan and the Pacific. About one-fourth of world maritime trade and a large share of the world’s oil supply passes through it, making it strategically vital.
Q6. Mention the main features of the equatorial climate.
Answer: The equatorial climate is found between 5°N and 5°S of the Equator. It has high temperature throughout the year (about 27°C), heavy rainfall (over 200 cm) distributed evenly through the year, and high humidity. It supports dense evergreen rainforests like the Amazon and Congo basins.
C. Long Answer Type Questions (5–6 Marks)
Q1. Describe the shape, size and motions of the Earth.
Answer: The Earth is the third planet from the Sun and the only one known to support life. Its shape is not a perfect sphere but a geoid — flattened at the poles and bulging at the equator because of rotation. Its equatorial diameter is about 12,756 km, polar diameter about 12,714 km, and total surface area roughly 510 million sq km, of which about 71% is water. The Earth performs two main motions. (i) Rotation: it spins on its tilted axis (23½°) from west to east once every 24 hours, producing day and night, the apparent rising and setting of the Sun, and deflection of winds and ocean currents. (ii) Revolution: it travels around the Sun in an elliptical orbit once every 365.25 days at an average speed of about 30 km per second. Revolution combined with the axial tilt is responsible for seasons, variation in length of day and night, and phenomena like equinoxes and solstices.
Q2. Explain the importance of the Equator, Prime Meridian and the International Date Line.
Answer: The Equator (0° latitude) is the imaginary line that divides the Earth into the Northern and Southern Hemispheres. It is the longest parallel and the basis for measuring all other latitudes; regions near it experience hot, equatorial climate. The Prime Meridian (0° longitude) passes through the Royal Observatory at Greenwich (UK) and divides the Earth into the Eastern and Western Hemispheres. It is the reference line for calculating Greenwich Mean Time (GMT) and longitudes worldwide. The International Date Line (IDL) roughly follows the 180° meridian through the Pacific Ocean, with deviations to avoid landmasses. When a traveller crosses it from west to east, a day is subtracted; from east to west, a day is added. Together these three lines provide the basis of the global grid, time zones and dating system.
Q3. Discuss the major rivers of the world and their importance.
Answer: The major rivers of the world include the Nile (Africa), longest river, supports Egyptian civilisation; Amazon (South America), largest by volume, drains the world’s biggest rainforest; Yangtze (China), longest in Asia, vital for agriculture, transport and hydroelectric power (Three Gorges Dam); Mississippi-Missouri (USA), backbone of agriculture and inland navigation in North America; Ganga (India), lifeline of the densely populated Indo-Gangetic plain and a sacred river; Volga (Russia), longest river in Europe, connected to seas through canals; and Congo (Central Africa), drains the Congo rainforest and has enormous hydroelectric potential. These rivers support irrigation, drinking water, fisheries, transport, hydropower and industries, and have nurtured great civilisations along their banks.
Q4. Describe the major climate types of the world.
Answer: World climates are broadly classified as: (i) Equatorial climate — hot and wet throughout the year with dense rainforests (Amazon, Congo). (ii) Tropical climate — high temperatures with distinct wet and dry seasons (savannas of Africa). (iii) Monsoon climate — seasonal reversal of winds bringing heavy summer rain and dry winters (India, Southeast Asia). (iv) Mediterranean climate — hot dry summers and mild wet winters; supports olives, citrus and vines (lands around the Mediterranean Sea, California, Cape Town). (v) Temperate climate — moderate temperatures with four distinct seasons (Western Europe, eastern USA, Japan); supports mixed farming and dense settlement. (vi) Polar climate — extremely cold throughout the year with very little precipitation; covered with ice and tundra (Arctic, Antarctic). Climate strongly influences vegetation, agriculture, settlement and lifestyle.
Q5. Explain world economic activities with reference to agricultural belts, mineral belts and industrial regions.
Answer: The world’s economic activities are concentrated in distinct belts and regions. Agricultural belts include the wheat belt of the Prairies (USA, Canada), Steppes (Russia, Ukraine) and Australia; the rice belt of monsoon Asia (India, China, Southeast Asia); and the cotton belt of southern USA, India, Egypt and Uzbekistan. Mineral belts include the iron ore belts of Brazil, Australia and India; the petroleum belts of West Asia (Saudi Arabia, Iraq, Iran), the Gulf of Mexico and Russia; and the coal belts of the USA, China, India and Russia. Industrial regions are concentrated in the Ruhr (Germany), the Great Lakes region (USA), the Kanto plain (Japan), the Yangtze valley (China) and the Mumbai-Pune cluster (India). These regions are linked by international trade routes such as the Suez Canal, Panama Canal, Strait of Hormuz and Strait of Malacca, while institutions such as the UN, WTO and IMF promote cooperation, free trade and economic stability.
Additional Multiple Choice Questions (MCQs)
Q1. The true shape of the Earth is —
(a) Sphere (b) Cylinder (c) Geoid (d) Cone
Answer: (c) Geoid.
Q2. How many hours does the Earth take to complete one rotation?
(a) 12 hrs (b) 18 hrs (c) 24 hrs (d) 36 hrs
Answer: (c) 24 hrs.
Q3. Indian Standard Time is based on —
(a) 75°E (b) 80°E (c) 82°30’E (d) 90°E
Answer: (c) 82°30’E.
Q4. The largest ocean in the world is —
(a) Atlantic (b) Indian (c) Arctic (d) Pacific
Answer: (d) Pacific.
Q5. Which is the largest hot desert in the world?
(a) Gobi (b) Sahara (c) Thar (d) Kalahari
Answer: (b) Sahara.
Q6. The Suez Canal connects —
(a) Atlantic & Pacific (b) Mediterranean & Red Sea (c) Black Sea & Caspian (d) Arctic & Pacific
Answer: (b) Mediterranean & Red Sea.
Q7. The headquarters of the IMF is located in —
(a) New York (b) Geneva (c) Washington D.C. (d) London
Answer: (c) Washington D.C.
Q8. The world’s longest river is —
(a) Amazon (b) Nile (c) Yangtze (d) Mississippi
Answer: (b) Nile.
Q9. The Tibetan Plateau is also known as —
(a) Roof of the World (b) Land of Rising Sun (c) Dark Continent (d) Land of Fire
Answer: (a) Roof of the World.
Q10. The 21 June is known as the —
(a) Vernal equinox (b) Autumnal equinox (c) Summer solstice (d) Winter solstice
Answer: (c) Summer solstice.
Fill in the Blanks
1. The shape of the Earth is called a __________. (geoid)
2. The Earth completes one revolution in __________ days. (365¼)
3. The __________ Canal connects the Atlantic and Pacific Oceans. (Panama)
4. The __________ Desert lies in northern Africa. (Sahara)
5. The __________ is the largest continent in the world. (Asia)
True or False
1. The Earth has six continents and four oceans. — False (seven continents and five oceans)
2. Indian Standard Time is 5 hours 30 minutes ahead of GMT. — True
3. The Amazon is the longest river in the world. — False (the Nile is longest; Amazon is largest by volume)
4. The Strait of Hormuz is important for the supply of petroleum. — True
5. The Mediterranean climate has hot wet summers and cold dry winters. — False (it has hot dry summers and mild wet winters)
Glossary
| Term | Meaning |
|---|---|
| Geoid | True shape of the Earth — flattened at poles, bulged at equator. |
| Rotation | Spinning of the Earth on its axis once in 24 hours. |
| Revolution | Movement of the Earth around the Sun once in 365¼ days. |
| Latitude | Imaginary east-west lines measuring distance north or south of the Equator. |
| Longitude | Imaginary north-south lines measuring distance east or west of the Prime Meridian. |
| Equator | 0° latitude dividing Earth into Northern and Southern Hemispheres. |
| Prime Meridian | 0° longitude passing through Greenwich, UK. |
| IDL | International Date Line — roughly along 180° longitude in the Pacific. |
| IST | Indian Standard Time, based on 82°30’E meridian (Mirzapur). |
| Equinox | Days when day and night are equal (21 March, 23 September). |
| Solstice | Days with longest or shortest daylight (21 June, 22 December). |
| Continent | Large continuous landmass; Earth has seven continents. |
| Ocean | Vast body of saline water; Earth has five oceans. |
| Plateau | Elevated flat-topped landform like the Tibetan or Deccan plateau. |
| Desert | Region with very low rainfall, e.g., Sahara, Gobi, Thar. |
| Monsoon | Seasonal reversal of winds bringing heavy rain to South and Southeast Asia. |
| Suez Canal | Canal in Egypt linking the Mediterranean and Red Seas. |
| Panama Canal | Canal linking the Atlantic and Pacific Oceans through Central America. |
| Strait of Hormuz | Narrow sea passage between Iran and Oman, vital for oil shipments. |
| Strait of Malacca | Sea route between the Indian and Pacific Oceans, between Malaysia and Indonesia. |
| UN | United Nations — global body for peace and cooperation, HQ New York. |
| WTO | World Trade Organization — regulates international trade, HQ Geneva. |
| IMF | International Monetary Fund — monitors global financial system, HQ Washington D.C. |
| Climate | Long-term average weather conditions of a region. |
| Population Density | Number of people living per square kilometre of land area. |
Quick Recap of Key Facts
| Feature | Important Facts |
|---|---|
| Largest continent | Asia (about 30% of Earth’s land area). |
| Smallest continent | Australia. |
| Largest ocean | Pacific Ocean. |
| Smallest ocean | Arctic Ocean. |
| Highest peak | Mount Everest (8,848.86 m), Himalayas. |
| Longest river | Nile, Africa. |
| Largest river by volume | Amazon, South America. |
| Largest hot desert | Sahara, North Africa. |
| Largest cold desert | Antarctic Desert. |
| Largest plateau | Tibetan Plateau (Roof of the World). |
| Most populous continent | Asia. |
| Most populous country | India (since 2023). |
Map Skills and Important Lines
Students should be able to identify the following on a world map: the seven continents and five oceans; the Equator (0°), Tropic of Cancer (23½°N), Tropic of Capricorn (23½°S), Arctic Circle (66½°N) and Antarctic Circle (66½°S); the Prime Meridian (0°) and the International Date Line (180°); the Sahara, Gobi, Atacama, Kalahari and Thar deserts; and major rivers including the Nile, Amazon, Yangtze, Mississippi, Ganga, Volga and Congo. Practising blank world maps regularly is the easiest way to score full marks in map-based questions of the HSLC examination.
Global vs Local Concerns
Many problems faced by humanity today cross national boundaries and require global action — climate change, ozone depletion, ocean pollution, loss of biodiversity, pandemics and refugee crises. At the same time, many issues are local — soil erosion, drinking water shortage, deforestation in a particular region or air pollution in a specific city. The principle “think globally, act locally” reminds us that protecting the planet begins with responsible behaviour at the local level: saving water and electricity, reducing plastic waste, planting trees, using public transport and supporting sustainable agriculture. International organisations like the UN, WTO and IMF, along with treaties like the Paris Agreement on climate change, attempt to coordinate national efforts toward shared global goals.
Keep revising these notes regularly. For more chapter-wise ASSEB Class 10 Social Science notes, MCQs and previous-year questions, stay connected with HSLC Guru.