EXERCISE

Q1. Write in brief about the earth’s lithosphere and hydrosphere.
Answer: The total surface area of the Earth is 510 million square kilometers. Of this, the lithosphere, or land portion, covers about 29% of the surface, which is 149 million square kilometers. This landmass is divided into seven continents: Asia, Africa, Europe, North America, South America, Oceania, and Antarctica.
The hydrosphere, or water portion, covers the remaining 71% of the Earth’s surface, which amounts to 361 million square kilometers. It is comprised of five major oceans: the Pacific, Atlantic, Indian, Arctic, and Southern oceans. Both the lithosphere and hydrosphere are fragmented and interpenetrate each other rather than forming two separate clusters.

Q2. How was the earth in the early days according to the Continental Drift Theory?
Answer: According to the Continental Drift Theory, in the early stage of the Earth’s history, about 300 million years ago, all of the planet’s landmass was joined together as a single continent called Pangaea. This supercontinent was surrounded by a single vast ocean known as Panthalassa. Over time, Pangaea fractured, and a narrow sea called the Tethys sea was formed, dividing it into a northern part, Angaraland or Laurasia, and a southern part, Gondwanaland.
During the Mesozoic era, roughly 250 million years ago, these two landmasses further broke apart and drifted towards the equator and the west, eventually forming the continents we see today.

Q3. Write briefly about the topography of the ocean floor.
Answer: While the surface of the oceans appears smooth, their bottom topography is actually very rugged and diverse. The ocean floor is not flat; it features landforms similar to those on the continents, such as ridges and trenches.
Moving from the coast towards the middle of the ocean, the depth gradually increases, revealing various landforms. These include the Continental Shelf (a shallow part up to about 200 meters deep), the Continental Slope (a considerably deeper part up to about 2,000 meters), and the Deep Sea Plain (up to about 4,000 meters deep). Other features include Oceanic Canyons, Oceanic Ridges, and Deep Sea Trenches. The deepest known point on Earth is the Mariana Trench in the Pacific Ocean, with a depth of 11,022 meters.

Q4. Write briefly about the distribution of oceans and continents.
Answer: The Earth’s surface has seven continents and five oceans, which are fragmented and interconnected rather than clustered together. Asia, Europe, and Africa form one large landmass, North America and South America form another, while Australia (part of Oceania) and Antarctica are separate landmasses.

The oceans surround these continents and are all connected. The Pacific Ocean lies between Asia, Australia, and the Americas; the Atlantic Ocean is between the Americas and Europe and Africa; the Indian Ocean is south of Asia, east of Africa, and west of Australia; the Arctic Ocean surrounds the North Pole, and the Southern Ocean surrounds Antarctica. Most of the Earth’s land (67%) is in the Northern Hemisphere, while most of the water (57%) is in the Southern Hemisphere.

Q5. Write in short about the landforms present on the earth’s land surface.
Answer: The Earth’s land surface, or lithosphere, has different landforms that are unevenly spread across continents. The main landforms include:

Q6. Briefly discuss the physical characteristics of Asia.
Answer:Asia is the largest continent, covering an area of about 44.6 million km², which is roughly 30% of the Earth’s land area, and it extends from 78° N to 1° N latitude and 25° E to 170° W longitude. The continent has diverse physical features, including high mountain ranges and plateaus such as the Himalayas, Ural Mountains, Tibetan Plateau, and Pamir Plateau, with Mount Everest being the world’s highest peak. Many major rivers like the Indus, Ganges, Brahmaputra, Yenisei, Ob, Lena, Amur, Hwang Ho, Yangtze Kiang, and Sikiang originate from these highlands and form fertile plains and deltas. Asia also has deserts such as the Gobi, Thar, and Arabian deserts, and lakes like Baikal. The continent shows a wide range of climates, from tropical in the south to polar in the north, which supports diverse vegetation and rich natural resources.

Q7. Give your answer with reasons: (a) Why do 90 per cent of the world’s total population concentrate in the northern hemisphere? (b) What is the reason behind lack of permanent human settlement in Antarctica?
Answer: (a) The primary reason for the concentration of 90% of the world’s population in the Northern Hemisphere is the uneven distribution of landmass on Earth. About 67% of the Earth’s lithosphere (land) is located in the Northern Hemisphere, which provides a significantly larger area for human settlement and economic activity. In contrast, the Southern Hemisphere has a much larger proportion of water (57%). The northern continents also generally have more favorable climates and natural resources, which are conducive to high population densities.

(b) The lack of permanent human settlement in Antarctica is due to its extremely harsh and unfavorable natural environment. Antarctica is a snow-covered continent located in the south polar region, where temperatures are extremely cold and the entire landmass is covered by a thick sheet of ice. These conditions make it impossible for permanent human habitation and agricultural activities. Scientific research stations are the only human presence on the continent.

Q8. Give short answer to the following questions:

(a) Which has created a natural boundary between Asia and Europe?
(b) Which is the longest mountain range of the world and where is it located?
(c) In terms of land area, which are the largest and smallest countries of the world?
(d) Which country of the world is spread to two continents?
(e) In terms of population, which are the largest and smallest countries of the world?
(f) What is the name of the major mountain range of North America? In which part of the continent is it located?
(g) Which is the world’s largest desert and where is it located?
(h) Write the names of two northerly and two easterly rivers of Asia.
(i) Write the names of one each of major mountain range, river and desert of Australia.
(j) Write the names of three countries of Europe located in the Mediterranean region.

Answer: 

Q9. Write short notes:
(a) Pangaea
(b) Arctic Ocean
(c) The Continent of Oceania
(d) The rivers of Asia
(e) The lakes of Africa
(f) The rivers of Europe
(g) The Appalachian Highland Region
(h) The lakes of North America

Answer:
(a) Pangaea: According to the Continental Drift Theory, Pangaea was a single supercontinent that existed approximately 300 million years ago, during the Permian Period. It was surrounded by a single ocean called Panthalassa. Over time, this landmass fractured and drifted apart to form the continents we know today.

(b) Arctic Ocean: With an area of about 14 million square km, the Arctic Ocean is the smallest ocean in the world. Its shape is circular as it surrounds the North Pole, and it is bordered by the northern parts of Asia, Europe, and North America. Due to its polar location, it remains covered with thick ice for most of the year.

(c) The Continent of Oceania: Oceania is the smallest continent, formed by the large island of Australia and numerous smaller and larger islands in the southwest Pacific Ocean, including New Zealand and New Guinea. It lies entirely in the Southern Hemisphere and is located south of Asia. Its land area is about 8 million square km, which is 5.4% of the world’s total land area.

(d) The rivers of Asia: Asia’s rivers are crucial for the continent’s fertile plains and deltas. Many rivers originate from the central highlands and flow in different directions. In the north, rivers like the Yenisei, Ob, and Lena flow towards the Arctic Ocean. Major rivers in the south-central part include the Indus, Ganges, and Brahmaputra. Rivers in the eastern part, like the Amur, Hwang Ho, Yangtze Kiang, and Sikiang, flow into the Pacific Ocean.

(e) The lakes of Africa: Africa has many rivers and lakes. Some of the most important lakes are Victoria, Albert, Tanganyika, Chad, Volta, Nyasa, Cabora Bassa, and Malawi. Lake Victoria is one of the largest freshwater lakes in the world.

(f) The rivers of Europe: Europe is rich in rivers and lakes. Some notable rivers include the Rhone and Seine in France; the Rhine and Elbe in Germany; the Danube, which flows through Austria, Hungary, and Romania; the Thames in the UK; and the Volga and Ural in Russia.

(g) The Appalachian Highland Region: This region is a major physiographic division of North America, located in the eastern part of the continent. It extends from Newfoundland in the north to Florida in the south. The region is characterized by rugged terrain, including hills, mountains, narrow valleys, and fragmented plateaus, and includes the Alleghany and Blue Ridge mountains.

(h) The lakes of North America: North America is home to numerous rivers and lakes, including some of the world’s largest freshwater lakes. The major lakes of the continent include Superior, Huron, Michigan, Erie, and Ontario, collectively known as the Great Lakes. Other important lakes are Great Bear, Great Slave, Winnipeg, and Great Salt Lake.

Q10. Write the differences between:
(a) Continental shelf and Continental slope
(b) Everest Peak and Godwin Austin Peak
(c) The Continent of Oceania and the Continent of Antarctica
(d) Gobi desert and Atacama desert

Answer:
(a) Continental shelf and Continental slope : The continental shelf is the shallow part of oceans and seas surrounding the coasts, with a depth of up to about 200 meters. It is relatively flat and extends from the shoreline to the point where the sea floor begins to slope downward.

On the other hand, the continental slope is the considerably deeper part of the ocean floor, located after the continental shelf. Its depth can reach up to about 2,000 meters, and it marks the transition from the shallow continental shelf to the deep ocean basin.

(b) Everest Peak and Godwin Austin Peak : Everest Peak is part of the Himalayan mountain system and has an altitude of 8,848 meters, making it the world’s highest peak.

On the other hand, Godwin Austin Peak is part of the Karakoram mountain system, with an altitude of 8,611 meters, making it the world’s second-highest peak.

(c) The Continent of Oceania and the Continent of Antarctica : The Continent of Oceania is the smallest continent, with a land area of about 8.1 million sq. km, located south of Asia in the Southern Hemisphere. It has a population of about 38 million and generally experiences a temperate climate with a wide range of weather conditions across its islands.

On the other hand, the Continent of Antarctica is the fifth-largest continent, covering about 13.2 million sq. km, located entirely in the south polar region of the Southern Hemisphere. It has no permanent human settlement and an extremely cold, snow-covered climate, making it inhospitable for permanent life.

(d) Gobi desert and Atacama desert : The Gobi Desert is located in Asia, mainly in Mongolia and China. It is a cold desert, characterized by rocky terrain and limited rainfall.

On the other hand, the Atacama Desert is located in South America, in the extremely dry parts of the Andes mountain ranges. It is a hot, arid desert and is considered one of the driest places on Earth.

Q11. Choose the correct answer:

(a) Which is the world’s second largest ocean?
(1) Pacific Ocean (2) Indian Ocean (3) Atlantic Ocean (4) Southern Ocean
Answer: (3) Atlantic Ocean

(b) Which is smallest continent of the world?
(1) North America (2) Europe (3) Antarctica (4) Oceania
Answer: (4) Oceania

(c) In which ocean Falkland island is located?
(1) Atlantic Ocean (2) Arctic Ocean (3) Pacific Ocean (4) Indian Ocean
Answer: (1) Atlantic Ocean

(d) Which sea has separated the continents of Asia and Africa?
(1) Mediterranean Sea (2) Red Sea (3) Caspian Sea (4) Arabian Sea
Answer: (2) Red Sea

(e) What has naturally separated Asia from Europe?
(1) Ural mountain range (2) Caucasus mountain (3) Caspian Sea (4) Volga river
Answer: (1) Ural mountain range

(f) In which continent is Ecuador located?
(1) North America (2) South America (3) Africa (4) Asia
Answer: (2) South America

(g) What is the capital of Brazil?
(1) Rio de Janeiro (2) Sao Paulo (3) Brasilia (4) Lima
Answer: (3) Brasilia