Topic outline

    • Water

      Q1. Fill in the blanks.

                              i.        Generally the warm ocean currents originate near equator.

                             ii.        The ocean bodies and the seas contain salty water.

                            iii.        The average salinity of the oceans is 35 parts per thousand.

                            iv.        Sodium chloride salt is mostly dissolved in ocean and sea water.

                             v.        Waves are formed when winds scrape across the ocean surface.


      Q2. True/False

                              i.        When air is heated, it expands, becomes lighter and goes up. True

                             ii.        Three-fourth of the earth surface is covered by water. True

                            iii.        The low tides also help in fishing. False

                            iv.        High tides help in navigation. True

      Q3. Which is the largest lake in the world?

      Ans. Caspian Sea


      Q4. What is a terrarium?

      Ans. It is an artificial enclosure for keeping small house plants.


      Q5. What is meant by the term salinity?

      Ans. Salinity is the amount of salt in grams present in 1000 grams of water.


      Q6. What is the salinity of Dead Sea?

      Ans. Dead Sea in Israel has salinity of 340 grams per litre of water.


      Q7. How is it possible to float in the Dead Sea?

      Ans. Swimmers can float in it because the increased salt content makes it dense.


      Q8. Why is the ocean salty?

      Ans. The water of the oceans is salty or saline as it contains large amount of dissolved salts.

      Q9. What is the effect of high tide?

      Ans. It is high tide when water covers much of the shore by rising to its highest level.


      Q10. What is the effect of low tide?

      Ans. It is low tide when water falls to its lowest level and recedes from the shore.


      Q11. What are the major sources of freshwater?

      Ans. The major sources of fresh water are the rivers, ponds, springs and glaciers.


      Q12. When is world water day celebrated?

      Ans. March 22 is celebrated as World Water Day when the need to conserve water is reinforced in different ways.


      Q13. What is the first indication of a tsunami?

      Ans. The first indication that tsunami is approaching is the rapid withdrawal of water from the coastal region, followed by destructive wave.


      Q14. Why is water essential for our survival?

      Ans. Water is absolutely essential for survival. Water alone can quench our thirst when we are thirsty.

      Q15. What happened to the Indira point during the tsunami of 2004?

      Ans. The Indira point in the Andaman and Nicobar islands got submerged after the tsunami.


      Q16. Name one warm ocean current and one cold ocean current?

      Ans. The Labrador Ocean current is cold current while the Gulf Stream is a warm current.


      Q17. What is Tsunami?

      Ans. Tsunami is a series of huge tidal waves caused by earthquakes or other disturbance under the sea.


      Q18. What are ocean currents?

      Ans. Ocean currents are streams of water flowing constantly on the ocean surface in definite directions.


      Q19. Where does the word tsunami come from and what does it mean?

      Ans. Tsunami is a Japanese word that means “Harbour waves” as the harbours get destroyed whenever there is tsunami.

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