Available Answers

1. 1.

   Multiple choice questions.

   1. Which of the following force hold atmosphere in its place?
      1. Electrostatic force
      2. Gravity
      3. Magnetic force
      4. Cohesive force
   2. The lowest layer of the atmosphere is:
      1. stratosphere
      2. thermosphere
      3. mesosphere
      4. troposphere
   3. Which layer of atmosphere considered best for flying of jet plane?
      1. Troposphere
      2. Exosphere
      3. Stratosphere
      4. Mesosphere
   4. Which of the following layer is responsible for the transmission of radio signals?
      1. Thermosphere
      2. Mesosphere
      3. Ionosphere
      4. Stratosphere
   5. What is the percentage of carbon dioxide gas in air?
      1. 0.03%
      2. 78%
      3. 21%
      4. 0.0005%
   6. Which of the following is used in soft drinks?
      1. Nitrogen gas
      2. Ozone gas
      3. Oxygen gas
      4. Carbon dioxide gas
   7. The gas which helps in burning is:
      1. carbon dioxide
      2. oxygen
      3. neon
      4. chlorine
2. 2.

   Fill in the blanks.

   absorbs, thermosphere, chlorination, water, dry ice, sedimentation

   1. ____________ is the method of water purification in which chlorine tablet is used to kill germs.
   2. The process of settling down of heavy insoluble impurities in water is called ____________.
   3. ____________ is called a universal solvent.
   4. Solid carbon dioxide is also called ____________.
   5. The ozone layer of the atmosphere ____________ harmful ultraviolet rays.
   6. Space shuttles orbit in ____________ of the atmosphere.
3. 3.

   Explain the two methods which are used for separating soluble impurities.

4. 4.

   How should water be purified for drinking?

5. 5.

   Name the different layers of the atmosphere.

6. 6.

   What is air composed of?