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Oceans and Continents – Class 6 Social Science notes, important questions and MCQs

NCERT Class 6 Social Science, chapter 2. Notes, key terms, important questions with answers and MCQs.

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Chapter overview

About 71 per cent of the earth's surface is covered by water and 29 per cent by land. The water forms five oceans and the land forms seven continents and many islands. Oceans support life, shape climate and trade, but can also bring disasters such as tsunamis and cyclones.

Oceans

  • The five oceans are the Pacific, Atlantic, Indian, Southern and Arctic Oceans.
  • The Pacific is the largest and deepest ocean; its Mariana Trench is the deepest known point on earth. The Arctic is the smallest.
  • Oceans give food, minerals and oxygen-producing plankton, control temperature and provide sea routes.
  • The tsunami of 26 December 2004 in the Indian Ocean caused huge loss of life in many countries, including India.

Continents and islands

  • The seven continents are Asia, Africa, North America, South America, Antarctica, Europe and Australia.
  • Asia is the largest and most populous continent; Australia is the smallest; Antarctica is covered with ice and has no permanent population.
  • Greenland is the largest island; India's island groups are the Andaman and Nicobar Islands (Bay of Bengal) and Lakshadweep (Arabian Sea).

Key terms

Ocean
a vast body of salt water covering most of the earth
Continent
a very large, continuous mass of land
Island
a piece of land surrounded by water on all sides
Tsunami
a series of huge sea waves usually caused by an undersea earthquake

Important questions with answers

Name the five oceans in order of size.2 marks

The five oceans in decreasing order of size are the Pacific, Atlantic, Indian, Southern and Arctic Oceans. The Pacific is the largest and deepest, and the Arctic is the smallest.

Why are oceans important for life on earth?3 marks

Oceans provide food such as fish and other sea animals, and minerals and salt. Tiny ocean plants called phytoplankton produce a large share of the earth's oxygen. Oceans store heat and keep temperatures moderate, bring rain through evaporation, and provide sea routes for trade.

What is a tsunami? How can people stay safe from it?4 marks

A tsunami is a series of huge sea waves caused mostly by an undersea earthquake, which pushes up the water above it. The waves travel fast across the ocean and become very high near the coast, destroying homes and lives, as in the 2004 Indian Ocean tsunami. People stay safe by heeding early warnings, moving quickly to high ground when the sea suddenly pulls back, and following evacuation drills; mangroves and coastal forests also reduce the force of waves.

Describe the distribution of land and water on the earth and the main features of the continents.5 marks

About 71 per cent of the earth's surface is water and only 29 per cent is land, and most of the land lies in the Northern Hemisphere. The land is divided into seven continents. Asia is the largest and most populous and includes India. Africa is the second largest and is crossed by the Equator. North and South America are joined by a narrow strip of land. Antarctica lies around the South Pole and is covered with ice. Europe is a small but densely populated continent joined to Asia, and Australia is the smallest continent, surrounded by oceans. Between the continents lie the five oceans, which connect people through trade and influence climate everywhere.

Quick revision

  • Water 71 per cent, land 29 per cent.
  • Five oceans; Pacific largest, Arctic smallest.
  • Seven continents; Asia largest, Australia smallest.
  • Greenland = largest island.

Exam tips

  • Use the mnemonic order of continents by size: Asia, Africa, North America, South America, Antarctica, Europe, Australia.
  • Mark the oceans and continents on a world outline map for practice.

Practice MCQs

  1. The largest ocean is the

    1. Atlantic
    2. Indian
    3. Arctic
    4. Pacific
    Show answer

    Answer: (d) Pacific. It covers about one-third of the earth.

  2. The smallest continent is

    1. Europe
    2. Australia
    3. Antarctica
    4. South America
    Show answer

    Answer: (b) Australia. Australia is both a continent and a country.

  3. Land surrounded by water on all sides is called

    1. a peninsula
    2. an island
    3. a plateau
    4. a continent
    Show answer

    Answer: (b) an island. Sri Lanka and Greenland are examples.

  4. The deepest known point on the earth is the

    1. Java Trench
    2. Mariana Trench
    3. Puerto Rico Trench
    4. Andaman Sea
    Show answer

    Answer: (b) Mariana Trench. It lies in the Pacific Ocean.

  5. Lakshadweep islands lie in the

    1. Arabian Sea
    2. Bay of Bengal
    3. Pacific Ocean
    4. Southern Ocean
    Show answer

    Answer: (a) Arabian Sea. They are coral islands off Kerala.

  6. Which continent has no permanent human population

    1. Africa
    2. Antarctica
    3. Australia
    4. Europe
    Show answer

    Answer: (b) Antarctica. It is covered with thick ice.

  7. A tsunami is most commonly caused by

    1. strong winds
    2. melting of glaciers
    3. an undersea earthquake
    4. high tide
    Show answer

    Answer: (c) an undersea earthquake. The sudden movement of the sea floor pushes up huge waves.

  8. About what share of the earth's surface is land

    1. 29 per cent
    2. 50 per cent
    3. 71 per cent
    4. 90 per cent
    Show answer

    Answer: (a) 29 per cent. The rest, about 71 per cent, is water.

All chapters of Class 6 Social Science

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.