1. Earth is known as the blue planet because of the presence of   Water   Atmosphere   The continents   Sky   Hint Half-n-half Clue   2. What is the melting point of ice?   0 oC   12 oC   32 oC   100 oC   Half-n-half Clue   3. Water exerts pressure on the walls and the bottom of the container in which it is placed.   True   False   4. Water which is absolutely pure and free from any impurity is known as   Distilled Water   Mineral Water   Spring Water   Boiled Water   Half-n-half Clue   5. Objects appear to weigh less in water than air.   True   False   6. Hardness of water is caused by the presence of certain salts in it.   True   False   7. Chlorine is added to drinking water to kill microbes that cause illness. This is known as   Chlorination   Elimination   Microbe Termination   Vaporization   Half-n-half Clue