CBSE Class 6 Social Science Oceans and Rivers Worksheet Set 18

Answer: (c) Atlantic. The Atlantic Ocean is shaped like the letter S.

Teacher's Note:
1. Look at it on a globe.
2. It lies between the Americas and Europe and Africa.

Answer: (b) Pacific Ocean. The Pacific covers about one-third of the Earth.

Teacher's Note:
1. It is also the deepest ocean.
2. It is larger than all land together.

Answer: (b) Bering Strait. The Bering Strait lies between Alaska and Russia.

Teacher's Note:
1. A strait links two large water bodies.
2. Palk Strait is near India and Sri Lanka.

Answer: (a) Lake Baikal. Lake Baikal in Russia is over 1600 m deep.

Teacher's Note:
1. It is also the oldest lake.
2. It holds fresh water.

Answer: True. The Southern Ocean circles Antarctica.

Teacher's Note:
1. It is the newest named ocean.
2. It joins the other three oceans.

Answer: False. The Indian Ocean is the one named after a country.

Teacher's Note:
1. India gives its name to the Indian Ocean.
2. Pacific means peaceful.

Answer: True. They flow very slowly down valleys under their own weight.

Teacher's Note:
1. Glaciers are rivers of ice.
2. They cut valleys.

Answer: True. They are fed by rain and melting snow, for example the Ganga.

Teacher's Note:
1. Non-perennial rivers dry up at times.
2. Glaciers feed many perennial rivers.

Answer: False. Cleaning polluted water is difficult and costly, so prevention is better.

Teacher's Note:
1. Pollution harms living things.
2. Prevent pollution at the source.

Answer: fluvial landforms, such as valleys, meanders and deltas.

Teacher's Note:
1. Fluvial refers to rivers.
2. Rivers both erode and deposit.

Answer: Estuaries. Sea water and river water mix in them.

Teacher's Note:
1. The Narmada and Tapi form estuaries.
2. A delta forms where silt is deposited.

Answer: Waterways. Ships and boats carry heavy goods cheaply.

Teacher's Note:
1. Rivers and oceans carry cargo.
2. Waterways need little fuel per tonne.

Answer: Java (Sunda) Trench.

Teacher's Note:
1. Trenches are deep ocean valleys.
2. It lies near Indonesia.

Answer: A bay is a smaller body of water partly enclosed by land, such as the Bay of Bengal. A gulf is deeper and more enclosed, such as the Gulf of Mannar.

Teacher's Note:
1. Both are inlets of the sea.
2. Size and enclosure separate them.

Answer: Perennial rivers flow throughout the year, like the Ganga. Non-perennial rivers carry water only in the rainy season and dry up in other months.

Teacher's Note:
1. Perennial rivers are fed by snow and rain.
2. Non-perennial rivers depend on rain.

Answer: Tributaries are small streams that join a main river. Distributaries are channels that branch off from a river near its mouth.

Teacher's Note:
1. Tributaries add water.
2. Distributaries carry water away.

Answer: The source is the place where a river begins, often in mountains. The mouth is where it ends by joining a sea, lake or larger river.

Teacher's Note:
1. Rivers flow from source to mouth.
2. Deltas form near the mouth.

Answer: A delta is a fan-shaped area formed by silt deposited at the mouth of a river. In an estuary, the river meets the sea in a wide funnel without a deposit.

Teacher's Note:
1. Deltas are built by deposits.
2. Estuaries have strong tides.

Answer: The Arctic Ocean lies to the north, the Pacific Ocean to the east and the Indian Ocean to the south.

Teacher's Note:
1. Asia is a large continent.
2. The west joins Europe.

Answer: Perennial rivers flow throughout the year. Non-perennial rivers are also called seasonal rivers.

Teacher's Note:
1. Seasonal rivers flow in the rains.
2. Perennial rivers never dry up.

Answer: The Pacific, Atlantic, Indian, Southern and Arctic Oceans.

Teacher's Note:
1. The Pacific is largest.
2. The Arctic is smallest.

Answer: The Arctic Ocean.

Teacher's Note:
1. It is mostly frozen.
2. It lies around the North Pole.

Answer: Oceans regulate climate, give rain, provide fish, salt, minerals and oil, and are a cheap route for trade. They are home to a huge variety of life.

Teacher's Note:
1. Oceans affect weather.
2. Many people depend on them for food.

Answer: Do not throw waste, plastic or chemicals into rivers and seas. Treat sewage and factory waste before releasing it.

Teacher's Note:
1. Prevent waste from reaching water.
2. Treatment plants help.

Answer: Rivers give water for drinking and irrigation, fertile soil, fish, cheap transport and hydroelectricity. Many cities and civilisations grew on their banks.

Teacher's Note:
1. Rivers support farming.
2. Dams use rivers for power.

Answer: In the upper course the river flows fast in steep land and cuts valleys and gorges. In the middle course it slows, widens and forms meanders. In the lower course it flows slowly over flat land, deposits silt and forms deltas.

Teacher's Note:
1. The river changes along its path.
2. Erosion is strongest upstream.

Answer: A tsunami is caused by an undersea earthquake, volcanic eruption or landslide that suddenly lifts or drops the sea floor. This sets up giant waves that travel across the ocean.

Teacher's Note:
1. The 2004 tsunami followed an earthquake.
2. Coastal areas are at risk.