5.3   Additional Questions :

Answer the following questions :

1.  What are the following :

(a) Terrarium          (b)  salinity       (c) World water day     (d)  tsunami
(e)  Spring tide        (f)  Neap tide    (g) Uses of high tides

Answers :

a) Terrarium   — It is an artificial enclosure for keeping small house plants.

b) Salinity— is the amount of salt in grams present in 1000 grams of water.

c) World water day —On this day the need to conserve water is reinforced in different ways all over the world.

d) Tsunami—is a Japanese word that means ‘harbour waves’ as the harbours get destroyed whenever there is tsunami. When an earthquake or volcanic eruption or underwater landslides shifts large amount of ocean water. A huge tidal wave is formed called tsunami.

e) Spring tide —during the full and new moon days, the sun , the moon and the earth are in the same line and the tides are highest. These tides are called spring tides.

f) Neap tide— When the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides.

g) Uses of high tides—High tides help in navigation and fishing. The rise and fall of water due to tides is being used to generate electricity in some places.

Fill in the blanks :

1.  ——— causes evaporation of water into water vapour.

2.  The major sources of ——– are rivers, ponds, springs and glaciers.

3.  ——- of the earth’s surface is covered by water.

4.  When the water on the surface of the ocean —- and —- alternately, they are called waves.

5.  The areas where the warm and cold currents meet provide the best ———-.

6.  The ——- Ocean current is cold current while the ——– is a warm current.

Answers :

1.  The sun’s heat    2.  fresh water               3.  three-fourth
4.  rise and fall         5.  fishing grounds       6.  Labrador  ,   Gulf stream.

Answer in short :

1.  What is the first indication that tsunami is approaching?
Ans : 
The first indication that tsunami is approaching is the rapid withdrawal of water from the coastal region, followed by destructive waves.

2.  Why can swimmers float in water in the Dead sea?
Ans :
  Swimmers can float in water in the Dead Sea there is large amount of salt content in the sea and it makes it dense.

3.  Where do the warm currents and cold currents originate?
Ans : 
The warm currents originate near the equator and move towards the poles. The cold currents carry water from polar or higher altitudes to tropical or lower latitudes.

4.  How are clouds formed?
Ans : 
The sun’s heat evaporates water into water vapour.  When the water vapour cools down, it condenses and form clouds.

5.  Write a paragraph on the tsunami that occurred in December 2004.
Ans : 
The tsunami that occurred in December 2004 ravaged the South and South East Asian coasts and was  the result of the earthquake. It travelled at a speed of about 800 km per hour and completely washed away some of the islands in the Indian Ocean.  It was the most devastating tsunami in the last several hundred years. The large damage caused to life and property was primarily a result of lack of monitoring, the early warning systems and knowledge among the coast dwellers of Indian Ocean. The worst affected coastal areas were of Andhra Pradesh, Tamil Nadu , Kerala , Pondicherry and the Andaman and Nicobar Islands.