NCERT Solutions for Class 7th: Ch 5 Water Geography Social Studies Our Enviroment
Page No: 37Exercises
1. Answer the following questions.
(i) What is precipitation?
Answer
Precipitation means any thing falling from the sky which include rain, snow, hail etc. on the surface of the earth when they become too heavy and unable to float in the air.
(ii) What is water cycle?
Answer
The process by which water continually changes its form and circulates between oceans, atmosphere and land is known as the water cycle.
(iii) What are the factors affecting the height of the waves?
Answer
Factors affecting the height of the waves:
(i) Speed off wind
(ii) Duration of wind
(iii) Distance the wind blows over water
(iv) Which factors affect the movement of ocean water?
Answer
Factors affecting the movement of ocean water:
(i) Temperature
(ii) Earthquake or volcanic eruption
(iii) Gravitational pull of the sun and the moon
(iv) Underwater landslides
(v) What are tides and how are they caused?
Answer
The rhythmic rise and fall of ocean water twice in a day is called a tide.
The strong gravitational pull exerted by the sun and the moon on the surface of the earth causes the tides.
(vi) What are ocean currents?
Answer
Ocean currents are streams of water flowing constantly on the ocean surface in definite directions.
2. Give reasons.
(i) Ocean water is salty.
(ii) The quality of water is deterioting.
Answer
(i) Ocean water is salty because it contains large amount of dissolved salts. Most of the salt is sodium chloride or the common table salt that we eat.
(ii) The quality of water is deterioting because we get it from polluted water sources. These water bodies are getting polluted due to dumping of untreated wastes, sewage, pesticides, toxicor decayed materials into it.
Page No: 3
3. Tick the correct answer.
(i) The process by which water continually changes its form and circulates between oceans, atmosphere and land
(a) Water cycle (b) Tides (c) Ocean currents
✓ (a) Water cycle
(ii) Generally the warm ocean currents originate near
(a) Poles (b) Equator (c) None of these
✓ (b) Equator
(iii) The rythmic rise and fall of ocean water twice in a day is called
(a) Tide (b) Ocean current (c) Wave
✓ (a) Tide
4. Match the following.
| (i) Caspian Sea | (a) Largest lake |
| (ii) Tide | (b) Periodic rise and fall of water |
| (iii) Tsunami | (c) Strong seismic waves |
| (iv) Ocean currents | (d) Streams of water moving along definite paths |
| - | (e) Water cycle |
Answer
| (i) Caspian Sea | (a) Largest lake |
| (ii) Tide | (b) Periodic rise and fall of water |
| (iii) Tsunami | (c) Strong seismic waves |
| (iv) Ocean currents | (d) Streams of water moving along definite paths |
Notes of Chapter 5 Water
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