Water - Solutions

 CBSE Class –VII Social Science

NCERT Solutions
Geography Chapter 5
Water

Q1. Answer the following questions.

  1. What is precipitation?
  2. What is water cycle?
  3. What are the factors affecting the height of the waves?
  4. Which factors affect the movement of ocean water?
  5. What are tides and how are they caused?
  6. What are ocean currents?

Answers:

  1. Precipitation: Precipitation is any form of liquid or solid water particles that fall from the atmosphere and reach the surface of Earth. This may be in the form of rain, hail, frost, fog, sleet or snow.
  2. Water Cycle: The process by which water continually changes its form and circulates between oceans, atmosphere and land is known as the water cycle.
  3. The factors affecting the height of waves are:
    • The high speed of the wind
    • Pushing action of winds blowing over the ocean
    • Duration of wind
    • The distance the wind blows on water
    • Earthquake
    • Volcanic Eruption
    • Underwater Landslides
  4. The factors affecting the movement of ocean water are:
    • Earth's rotation
    • Salinity
    • Prevailing winds
    • Variation in Temperature
    • The gravitational pull of sun and moon
    • Earthquakes and volcanic eruptions
  5. Tides: The rhythmic and alternate, rise and fall of ocean water twice a day is called a tide.
    Tides are caused due to the gravitational pull exerted by the sun and the moon on the earth's surface.
    The moon is closer to the Earth is responsible for tides to a greater extent than the Sun.
    When the level of the Water is highest, it is called High Tide.
    When the level of water is the lowest, it is called Low Tide.
  6. Ocean currents: Large Scale movement of water in the oceans in a definite direction are called ocean currents. The ocean currents are like rivers in the ocean that are of thousands of kilometers in length and very wide also. The ocean currents are of two types. That are- Warm Currents and Cold Currents. For example, the Labrador ocean current is cold current and the Gulf Stream is warm current.

Q2. Give reasons.
(i) Ocean water is salty.
Ans. Ocean water is salty because it contains large amounts of dissolved salts. Most of the salt is sodium chloride or the common table salt that we eat.
(ii) The quality of water is deteriorating.
Ans: The quality of water is deteriorating because of the following reasons:

  • The garbage we throw in the ponds and the rivers.
  • The dumping of toxic liquids in the rivers and oceans.
  • Ocean mining in the deep sea is the main source of ocean water pollution.
  • Chemicals and polluted water released from industries that polluted water.
  • Remains of the harmful insecticides and pest resistants flowing in from the fields.
  • Unburnt or half burnt corpses of men and animals thrown in water bodies.
  • People washing clothes in rivers and ponds.

Q3.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
Ans: (a) Water Cycle
(ii) Generally, the warm ocean currents originate near
(a) Poles (b) Equator (c) None of these
Ans: (b) Equator
(iii) The rhythmic rise and fall of ocean water twice a day is called
(a) Tide (b) Ocean currents ( c) Wave
Ans: (a) Tide

Q4. Match the following:

(i)Caspian Sea(a)Periodic rise and fall of water
(ii)Tide(b)Largest lake
(iii)Tsunami(c)Streams of water moving in definite paths
(iv)Ocean Currents(d)Strong seismic waves

Ans:

(i)Caspian Sea(b)Largest lake
(ii)Tide(a)Periodic rise and fall of water
(iii)Tsunami(d)Strong seismic waves
(iv)Ocean Currents(c)Streams of water moving in definite paths

Q5. For fun. Be a detective
(i) The name of one river is hidden in each of the sentences below. Spot it.
Example: Mandra, Vijayalakshmi and Surinder are my best friends.
Ans: Ravi.

(a) The snake charmer's bustee, stables where horses are housed, and piles of wood, all caught fire accidentally. (Hint: Another name for river Brahmaputra)
Ans: Teesta.

(b) The conference manager put pad, material for reading and a pencil for each participant: ( Hint: A distributary on the Ganga-Brahmaputra delta? )
Ans: Padma.

(c) Either jealousy or anger causes a person's fall. ( Hint: Name of juicy fruit!)
Ans: Orange.

(d) Bhavani germinated the seeds in a pot. (Hint: Look for her in West Africa)
Ans. Niger.

(e) ''I am a zonal champion now," declared the excited athletic. (Hint: The river that has the biggest basin in the world)
Ans: Amazon.

(f) The tiffin box rolled down and all the food fell in dusty potholes. ( Hint: Rises in India and journeys through Pakistan)
Ans: Indus.

(g) Malini leaned against the pole when she felt that she was going to faint. (Hint: Her delta in Egypt is famous)
Ans: Nile.

(h) Samantha mesmerized everybody with her magic tricks. (Hint: London is situated on her estuary)
Ans: Thames.

(i) "In this neighborhood, please don't yell! Owners of these houses like to have peace." warned my father when we moved into our new flat. (Hint: colour !)
Ans: Yellow.

(j) 'Write the following words. Marc! "On," "go,'', "in".... said the teacher to the little boy in KG Class. ( Hint: Rhymes with 'bongo')
Ans: Congo.