Major Domains of the Earth: NCERT Exercise Solutions
Welcome to the complete NCERT exercise solutions for Class 6 Social Science Geography Chapter 5 — Major Domains of the Earth. This chapter introduces you to the four major domains of our planet: the Lithosphere, Hydrosphere, Atmosphere, and Biosphere. You will learn about continents, oceans, and how these domains interact to make Earth a unique planet that supports life.
Every question below is answered step-by-step in simple language so you can write well in your exams. Key terms are highlighted, and extra practice questions are included at the end.
How to Use This Page
1. Read the Key Concepts table first for a quick recap of all important terms. 2. Follow the Intext Questions to understand concepts as they appear in the chapter. 3. Study the Chapter-End Exercise Solutions — these are the exact NCERT questions with full answers. 4. Attempt the MCQ Practice section to test yourself before exams. 5. Review the Common Mistakes and Exam Checklist to avoid losing marks.
Key Concepts (Quick Recap)
| Term | Definition |
|---|
| Lithosphere | The solid portion of the Earth consisting of the crust and the uppermost part of the mantle; includes continents, islands, and the ocean floor. |
| Hydrosphere | The domain of water comprising all water bodies — oceans, seas, rivers, lakes, glaciers, groundwater, and water vapour. |
| Atmosphere | The thin layer of air that surrounds the Earth; composed of nitrogen (78%), oxygen (21%), and other gases (1%). |
| Biosphere | The narrow zone where land, water, and air interact with each other to support life; includes all living organisms. |
| Continent | A large continuous landmass on the Earth's surface. There are seven continents. |
| Ocean | A vast body of salt water covering most of the Earth's surface. There are five major oceans. |
| Troposphere | The lowest layer of the atmosphere, extending up to about 12 km; where all weather phenomena occur. |
| Stratosphere | The layer above the troposphere (12–50 km); contains the ozone layer that protects us from harmful ultraviolet rays. |
| Pacific Ocean | The largest and deepest ocean, covering about one-third of the Earth's surface. |
| Atlantic Ocean | The second-largest ocean, shaped like the letter 'S'; located between the Americas and Europe/Africa. |
| Indian Ocean | The third-largest ocean, the only one named after a country (India). |
| Mt. Everest | The highest point on the Earth's surface at 8,848 metres above sea level, located in the Himalayas. |
| Mariana Trench | The deepest point on the Earth, located in the Pacific Ocean at about 11,022 metres below sea level. |
Intext Questions
Q1. Why is the Earth called a unique planet in the solar system?
Answer
The Earth is called a unique planet because it is the only planet in the solar system known to support life. This is possible because of three special conditions: (a) the right distance from the Sun gives it the right temperature range, (b) the presence of water in liquid form, and (c) a breathable atmosphere containing oxygen. No other planet has all three conditions together.
Q2. Why is life possible on the Earth and not on other planets?
Answer
Life on Earth is possible because of the presence of: (i) Lithosphere — the solid surface that provides a base for living organisms; (ii) Hydrosphere — water which is essential for all life processes; (iii) Atmosphere — the air we breathe, which also protects us from harmful solar radiation. The interaction of these three domains creates the Biosphere, the zone of life. Other planets lack one or more of these essential domains.
Q3. How do the four domains of the Earth interact with each other?
Answer
The four domains of the Earth are closely connected: (a) The lithosphere provides the land surface and minerals; (b) The hydrosphere provides water that shapes the land through erosion and weathering; (c) The atmosphere provides gases necessary for life and drives weather patterns; (d) The biosphere is the zone where all three domains interact — living organisms depend on land, water, and air for their survival. For example, plants (biosphere) grow in soil (lithosphere), need water (hydrosphere), and use carbon dioxide from the air (atmosphere) for photosynthesis.
Q4. Why is the atmosphere important for living organisms?
Answer
The atmosphere is important for several reasons: (i) It contains oxygen, which is essential for breathing; (ii) It has the ozone layer in the stratosphere that blocks harmful ultraviolet rays from the Sun; (iii) It acts as a blanket, keeping the Earth warm by trapping heat (greenhouse effect); (iv) It produces weather — rain, wind, and temperature changes that shape the surface; (v) It protects the Earth from meteoroids that burn up due to friction in the atmosphere.
Q5. What percentage of the Earth's surface is covered by water and by land?
Answer
About 71% of the Earth's surface is covered by water (hydrosphere) and only 29% is covered by land (lithosphere). This is why the Earth appears blue from space and is often called the Blue Planet.
Chapter-End Exercise Questions
Q1. Answer the following questions briefly.
(a) Why is the Earth called the Blue Planet?
The Earth is called the Blue Planet because about 71% of its surface is covered by water. When seen from space, the large expanse of oceans makes the Earth appear blue in colour. No other planet in the solar system has such a large amount of water on its surface.
(b) What is a continent? Name the seven continents.
A continent is a large, continuous landmass on the Earth's surface. The seven continents are:
1. Asia — the largest continent, covering about one-third of the total land area. 2. Africa — the second-largest continent, home to the Sahara Desert. 3. North America — the third-largest continent. 4. South America — has the Amazon Rainforest, the largest tropical rainforest. 5. Antarctica — the coldest, driest, and windiest continent; permanently covered with ice. 6. Europe — much smaller than Asia; separated from Asia by the Ural Mountains. 7. Australia — the smallest continent, also called an island continent.
(c) Name the continents that the Equator passes through.
The Equator passes through three continents: South America, Africa, and Asia. The Equator is an imaginary line that divides the Earth into the Northern Hemisphere and the Southern Hemisphere.
(d) Name the two continents that the Tropic of Capricorn passes through.
The Tropic of Capricorn (23½° S) passes through Australia and South America. It also touches the southern tip of Africa, but the primary two continents named in NCERT are Australia and South America.
Q2. Tick the correct answers.
(a) The Earth is called the Blue Planet because:
- (i) It has a blue sky ☐
- (ii) Most of its surface is covered by water ✓
- (iii) It appears blue from space due to water ✓
- (iv) It has blue mountains ☐
Answer(ii) and (iii) — Most of its surface (71%) is covered by water, and it appears blue from space.
(b) Which is the largest continent?
- (i) Africa ☐
- (ii) Europe ☐
- (iii) Asia ✓
- (iv) North America ☐
Answer(iii) Asia — It is the largest continent, covering about one-third of the total land area of the Earth.
(c) Which is the deepest ocean trench?
- (i) Mariana Trench ✓
- (ii) Puerto Rico Trench ☐
- (iii) Java Trench ☐
- (iv) Tonga Trench ☐
Answer(i) Mariana Trench — Located in the Pacific Ocean, it is about 11,022 metres deep.
(d) Which gas makes up the largest portion of the atmosphere?
- (i) Oxygen ☐
- (ii) Carbon dioxide ☐
- (iii) Nitrogen ✓
- (iv) Hydrogen ☐
Answer(iii) Nitrogen — It makes up about 78% of the atmosphere.
(e) Which layer of the atmosphere contains the ozone layer?
- (i) Troposphere ☐
- (ii) Mesosphere ☐
- (iii) Thermosphere ☐
- (iv) Stratosphere ✓
Answer(iv) Stratosphere — The ozone layer is found in the stratosphere, between 20 and 50 km above the Earth's surface.
Q3. Fill in the blanks.
1. The _________ is the solid part of the Earth.
AnswerLithosphere 2. The _________ Ocean is the largest ocean on the Earth. Answer: Pacific 3. The _________ is the narrow zone where land, water, and air interact to support life. Answer: Biosphere 4. Nitrogen makes up about _________ per cent of the atmosphere. Answer: 78 5. The highest point on the Earth's surface is _________. Answer: Mt. Everest (8,848 m) 6. The deepest point on the Earth is the _________ in the Pacific Ocean. Answer: Mariana Trench 7. _________ is the smallest continent. Answer: Australia 8. The layer of atmosphere closest to the Earth's surface is the _________. Answer: Troposphere
Q4. True or False.
1. The lithosphere includes only the land surface and not the ocean floor.
AnswerFalse — The lithosphere includes the crust and uppermost mantle, which covers both continental landmasses and the ocean floor.
2. The Pacific Ocean is the smallest ocean.
AnswerFalse — The Pacific Ocean is the largest and deepest ocean. The Arctic Ocean is the smallest.
3. The biosphere is the zone where all three domains interact.
AnswerTrue — The biosphere is the narrow zone where the lithosphere, hydrosphere, and atmosphere come together and support life.
4. Australia is both a continent and a country.
AnswerTrue — Australia is the only continent that is also a single country.
5. The atmosphere has no role in protecting the Earth from meteoroids.
AnswerFalse — The atmosphere protects the Earth by burning up most meteoroids through friction before they reach the surface.
6. Europe is the smallest continent.
AnswerFalse — Australia is the smallest continent. Europe is the second smallest.
7. The Southern Ocean surrounds Antarctica.
AnswerTrue — The Southern Ocean, also called the Antarctic Ocean, surrounds the continent of Antarctica.
8. Asia and Europe are separated by the Ural Mountains.
AnswerTrue — The Ural Mountains form the traditional boundary between Europe and Asia.
Q5. Match the Column.
| Column A | Column B |
|---|
| (i) Lithosphere | (a) Narrow zone of life |
| (ii) Hydrosphere | (b) Solid part of the Earth |
| (iii) Atmosphere | (c) Domain of water |
| (iv) Biosphere | (d) Thin layer of air |
| (v) Pacific Ocean | (e) Largest ocean |
| (vi) Mt. Everest | (f) Highest point on Earth |
| (vii) Mariana Trench | (g) Deepest point on Earth |
Answer
- (i) Lithosphere → (b) Solid part of the Earth
- (ii) Hydrosphere → (c) Domain of water
- (iii) Atmosphere → (d) Thin layer of air
- (iv) Biosphere → (a) Narrow zone of life
- (v) Pacific Ocean → (e) Largest ocean
- (vi) Mt. Everest → (f) Highest point on Earth
- (vii) Mariana Trench → (g) Deepest point on Earth
Additional Important Questions
Q6. Why is the biosphere important for living organisms?
Answer
The biosphere is important for living organisms because it is the only zone on Earth where life exists. It is the narrow zone where the lithosphere (land), hydrosphere (water), and atmosphere (air) interact with each other. All living organisms — plants, animals, and microorganisms — depend on this interaction for food, shelter, and reproduction. Without the biosphere, no life would be possible on Earth.
Q7. Describe the different layers of the atmosphere.
Answer
The atmosphere is divided into five layers, starting from the Earth's surface:
1. Troposphere (0–12 km): The lowest layer where all weather occurs. Temperature decreases with height. It contains most of the atmosphere's water vapour. 2. Stratosphere (12–50 km): Contains the ozone layer which absorbs harmful ultraviolet radiation from the Sun. Temperature increases with height in this layer. 3. Mesosphere (50–80 km): The middle layer where most meteoroids burn up. Temperature again decreases with height. 4. Thermosphere (80–400 km): Temperature rises sharply due to absorption of solar radiation. The ionosphere, which helps in radio communication, is located here. 5. Exosphere (400 km and above): The outermost layer where the atmosphere merges into space. It contains very thin air.
Q8. Why is the Pacific Ocean called the largest ocean?
Answer
The Pacific Ocean is called the largest ocean because: (i) It covers about one-third of the Earth's total surface area; (ii) It is the deepest ocean, with the Mariana Trench reaching a depth of about 11,022 metres; (iii) It is spread over an area of approximately 165.25 million square kilometres, making it larger than all the land area on Earth combined; (iv) It stretches from the Arctic in the north to the Southern Ocean in the south, and from Asia and Australia in the west to the Americas in the east.
MCQ Practice
1. What percentage of the Earth's surface is covered by water?
Answer
- (A) 50% ☐
- (B) 61% ☐
- (C) 71% ✓
- (D) 81% ☐
Answer(C) 71% — About 71% of the Earth's surface is covered by water.
2. Which is the smallest continent?
Answer
- (A) Europe ☐
- (B) Antarctica ☐
- (C) Australia ✓
- (D) South America ☐
Answer(C) Australia — It is the smallest continent as well as an island continent.
3. Which gas constitutes about 78% of the atmosphere?
Answer
- (A) Oxygen ☐
- (B) Carbon dioxide ☐
- (C) Nitrogen ✓
- (D) Argon ☐
Answer(C) Nitrogen — Nitrogen makes up 78% of the atmosphere by volume.
4. The Mariana Trench is located in which ocean?
Answer
- (A) Atlantic Ocean ☐
- (B) Indian Ocean ☐
- (C) Arctic Ocean ☐
- (D) Pacific Ocean ✓
Answer(D) Pacific Ocean — The Mariana Trench is the deepest point on Earth and lies in the western Pacific Ocean.
5. The Himalayas are an example of which domain?
Answer
- (A) Hydrosphere ☐
- (B) Atmosphere ☐
- (C) Lithosphere ✓
- (D) Biosphere ☐
Answer(C) Lithosphere — The Himalayas are mountain ranges, which are part of the solid land portion of the Earth.
6. The ozone layer is found in which layer of the atmosphere?
Answer
- (A) Troposphere ☐
- (B) Stratosphere ✓
- (C) Mesosphere ☐
- (D) Exosphere ☐
Answer(B) Stratosphere — The ozone layer lies within the stratosphere, approximately 20–50 km above the Earth.
7. Which is the only ocean named after a country?
Answer
- (A) Pacific Ocean ☐
- (B) Atlantic Ocean ☐
- (C) Indian Ocean ✓
- (D) Arctic Ocean ☐
Answer(C) Indian Ocean — The Indian Ocean is the only ocean named after a country, India.
8. Which continent is also called the White Continent?
Answer
- (A) Europe ☐
- (B) Australia ☐
- (C) Asia ☐
- (D) Antarctica ✓
Answer(D) Antarctica — Antarctica is called the White Continent because it is permanently covered with a thick sheet of ice and snow.
9. Which ocean is shaped like the letter 'S'?
Answer
- (A) Pacific Ocean ☐
- (B) Atlantic Ocean ✓
- (C) Indian Ocean ☐
- (D) Arctic Ocean ☐
Answer(B) Atlantic Ocean — The Atlantic Ocean is the second-largest ocean and is roughly 'S'-shaped.
10. What is the height of Mt. Everest above sea level?
Answer
- (A) 6,848 m ☐
- (B) 7,848 m ☐
- (C) 8,848 m ✓
- (D) 9,848 m ☐
Answer(C) 8,848 m — Mt. Everest, the highest peak on Earth, stands at 8,848 metres above sea level.
Common Mistakes to Avoid
1. Confusing "continent" with "country" — A continent is a large landmass; a country is a political unit within a continent. For example, Asia is a continent, not a country, and it contains many countries like India, China, and Japan.
2. Writing "water" instead of "hydrosphere" or "land" instead of "lithosphere" — In exam answers, use the proper domain names (Lithosphere, Hydrosphere, Atmosphere, Biosphere) rather than everyday words. The NCERT textbook uses these specific terms, and examiners expect them.
3. Forgetting that the Arctic Ocean is the smallest ocean — Many students mistakenly write that the Indian Ocean is the smallest. The correct order from largest to smallest is: Pacific > Atlantic > Indian > Southern > Arctic.
4. Mixing up the layers of the atmosphere — Remember the correct order from bottom to top: Troposphere → Stratosphere → Mesosphere → Thermosphere → Exosphere. A useful trick: "The Sun Melts The Exosphere" (Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere).
5. Writing that nitrogen makes up 21% and oxygen 78% — This is the most common mix-up. Nitrogen makes up 78% and oxygen makes up 21% of the atmosphere. Always double-check these percentages before writing.
6. Confusing the Tropic of Capricorn and Tropic of Cancer — The Tropic of Capricorn (23½° S) passes through Australia and South America, while the Tropic of Cancer (23½° N) passes through Asia, Africa, and North America. Do not mix up the two.
Exam Checklist
Before your exam, make sure you can answer each of the following:
- [ ] Can you name all four major domains and describe each one briefly?
- [ ] Can you list all seven continents in order of size (largest to smallest)?
- [ ] Can you list all five oceans in order of size (largest to smallest)?
- [ ] Can you explain why the Earth is called the Blue Planet?
- [ ] Can you name the continents through which the Equator passes?
- [ ] Can you name the continents through which the Tropic of Capricorn passes?
- [ ] Can you state the composition of the atmosphere (nitrogen 78%, oxygen 21%, other gases 1%)?
- [ ] Can you list the five layers of the atmosphere in the correct order?
- [ ] Can you explain why the biosphere is important for living organisms?
- [ ] Can you identify the highest point (Mt. Everest, 8,848 m) and deepest point (Mariana Trench, 11,022 m) on Earth?
- [ ] Can you name the ocean that is shaped like the letter 'S' (Atlantic)?
- [ ] Can you name the only ocean named after a country (Indian Ocean)?
Tip: Revise the Key Concepts table daily and try writing the answers in your own words. Understanding the "why" behind each fact (e.g., why the atmosphere is important, why the biosphere exists) will help you score better than rote memorisation.
