Water
NCERT Solution
Give Reasons:
Question 1: Ocean water is salty.
Answer: Ocean water contains large amounts of dissolved salts. Hence it is salty.
Question 2: 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:
Question 1: The process by which water continually changes its form and circulates between oceans, atmosphere and land
- Water Cycle
- Tides
- Ocean currents
Answer: (a) Water Cycle
Question 2: Generally the warm ocean currents originate near
- Poles
- Equator
- None of these
Answer:(b)Equator
Question 3: The rythmic rise and fall of ocean water twice in a day is called
- Tide
- Ocean current
- Wave
Answer: (a) Tide
Answer the following questions:
Question 1: 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.
Question 2: 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.
Question 3: What are the factors affecting the height of the waves?
Answer: Speed of the wind and wind duration.
Question 4: 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.
Question 5: 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.
Question 6: What are ocean currents?
Answer: They are the streams of water flowing constantly on the ocean surface in definite directions.
Match the following:
| Column I | Column 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