Available Answers

1. 1.

   Multiple choice questions:

   1. Which of the following changes into clouds, rain, fog and snow?
      1. water vapour
      2. oxygen
      3. hydrogen
      4. argon
   2. The process which is used to remove insoluble impurities from water is:
      1. sedimentation
      2. chlorination
      3. distillation
      4. evaporation
   3. Impure water contains many disease causing germs like those of:
      1. cholera
      2. jaundice
      3. dysentery
      4. all of these
   4. This water is mainly used in car batteries, science experiments and in medicines:
      1. boiled water
      2. tap water
      3. distilled water
      4. sea water
   5. Which gas is present in air in the maximum percentage?
      1. oxygen
      2. carbon dioxide
      3. nitrogen
      4. argon
2. 2.

   List some of the gases found in the air.
3. 3.

   Name the various layers of the atmosphere.
4. 4.

   Why do we feel uncomfortable on a humid day?
5. 5.

   Why should drinking water be purified?
6. 6.

   What is meant by sedimentation and decantation?