Water

NCERT Solution

Give Reasons:

Ocean water is salty.

Answer: Ocean water contains large amounts of dissolved salts. Hence it is salty.

The quality of water is deteriorating.

Answer: Water quality is deteriorating because of pesticides, toxic and hazardous wastes, litter and rubbish, decayed organic materials and chemicals.


Multiple Choice Questions:

The process by which water continually changes its form and circulates between oceans, atmosphere and land

  1. Water Cycle
  2. Tides
  3. Ocean currents

    Answer: (a) Water Cycle

Generally the warm ocean currents originate near

  1. Poles
  2. Equator
  3. None of these

    Answer:(b)Equator

The rythmic rise and fall of ocean water twice in a day is called

  1. Tide
  2. Ocean current
  3. Wave

    Answer: (a) Tide

Answer the following questions:

What is precipitation?

Answer: It is the process in which the droplets of water (clouds), on becoming too heavy and unable to float in the air, come down on the earth.

What is water cycle?

Answer: The process by which water continually changes its form and circulates between oceans, atmosphere and land is called the water cycle.

What are the factors affecting the height of the waves?

Answer: Speed of the wind and wind duration.

Which factors affect the movement of ocean water?

Answer: Speed of the wind, earthquake, volcanic eruption, underwater landslides and the gravitational pull exerted by the sun and the moon on the earth’s surface.

What are tides and how are they caused?

Answer: The rhythmic rise and fall of ocean twice in a day is called a tide. Tides are caused by the strong gravitational pull exerted by the sun and the moon on the earth’s surface.

What are ocean currents?

Answer: They are the streams of water flowing constantly on the ocean surface in definite directions.


Match the following:
Column IColumn II
(i) Caspian Sea(a) Largest lake
(ii) Tide(b) Periodic rise and fall of water
(iii) Tsunami(c) Strong seismic waves
(iv) Ocean current(d) Streams of water moving along definite paths
(e) Water cycle

Answer: (i)a, (ii)b, (iii)c, (iv)d



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