CLASS-7 CHAPTER-5 WATER SURROUNDING THE EARTH

(D) ANSWER THE FOLLOWING QUESTION IN BRIEF-----

1.QUESTION-

On what factors does the height of a wave depend?

ANSWER- 

The height of waves depends on the speed of wind and the duration of wind blowing from a particular direction.

2.QUESTION

Define an ocean current .

ANSWER

The ocean current is the continuous movement of a mass of water in a particular direction. Ocean currents are broadly of two types, ie. Cold currents and Warm currents.

3.QUESTION

How are tides caused?

ANSWER-

Tides are caused due to the gravitational pull of the moon and the sun.

4.QUESTION

Name the important components of the Water cycle.

ANSWER

The important components of water cycle are-

The sun

Ocean

Temperature etc.

5.QUESTION

Name three valuable resources which are found in abundance in the Ocean.

ANSWER-

Three valuable resources which are found in abundance in the ocean are-

Gold

Copper

Mineral Oil

(E) Answer the following questions-

1.QUESTION

How are tides useful to us?

ANSWER

Tides are useful to us in many ways high tide enables big ships to enter the harbor or soil out of the harbor, Now a days, tide energy is harnessed to generate electricity in coastal areas.

2.QUEATION

How are ocean beneficial to us in improving the quality of life?

ANSWER

Ocean are beneficial to us in improving the quality of life in many ways-

1.The oceans facilitate countries and regions to trade with one another.

2.Goods can be moved in a very large quality by ships and the transportation is cheaper than any other mode of transport.

3.The marine environment  provides animal and plant life for food and trade in abundance. Some of the valuable mineral resources are also found in the ocean floor.

3.QUESTION

Explain the water cycle with the help of a diagram.

ANSWER-

Water of the oceans is converted into water vapours to the heat of the sun by the process of evaporation. The evaporated vapours rise up in the atmosphere and condense into tiny crystals of ice or droplets of water to form clouds. When the condensed ice crystals or water droplets grow in size and are unable to float, they fall down over the earth surface as precipitation. It is because of this never ending circulation that the process is described as water cycle.

4.QUESTION

Explain three effects of ocean currents.

ANSWER

Three effects of ocean currents are as follows-

1.The ocean currents play an important role in influencing the climate of the coastal region of the continents.

2.The confluence of warm and cold currents provides ideal conditional for plentiful growth of plankton, which is a good for the marine life.

3.The ocean currents also help in navigation.

5.QUESTION

Suggest four ways to help people affected by devastation due to Tsunami.

ANSWER

Government agencies, Non Governmental Organization , Resident Welfare Associations, business organizations, shopkeepers, school and colleges provided relief to the victims by donating the Money, cloths, medicines, beddings, tents etc. Media played and important role in mobilizing public help for the victims of Tsunami.