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1. 1.

   Can you think of some uses of air? List any three.

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   Answer:

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   Uses of Air: Breathing: All living beings need air to breath...

2. 2.

   Fill in the blanks with the correct words.

   1. Air is a ______________ (solution/mixture) of gases.
   2. ______________ (Oxygen/Nitrogen) constitutes about 78% or air.
   3. ______________ (Oxygen/Nitrogen) is needed for burning.
   4. The form of water that is present in air is ______________ (water vapour/liquid water).
   5. Air contains dust and ______________ (smoke/fire).
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   1. mixture
   2. Nitrogen
   3. Oxygen
   4. water vapour
   5. smoke
3. 3.

   Say T for the true statement and F for the false one.

   1. Plants use oxygen to make their own food.
   2. A cockroach respires through its skin.
   3. Aquatic animals take in air dissolved in water.
   4. The balance of oxygen and carbon dioxide in the atmosphere is maintained through respiration in plants and animals, and by photosynthesis in plants.
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   1. F Plants use carbon dioxide and sunlight to make their own f...
   2. F A cockroach respires through tiny tubes called tracheae, not t...
   3. ...
   4. ...
4. 4.

   Choose the correct option.

   1. Air is made up of
      1. one gas
      2. three gases
      3. several gases
      4. none of them
   2. Gas with the highest percentage in air is
      1. oxygen
      2. nitrogen
      3. carbon dioxide
      4. water vapour
   3. Air contains
      1. oxygen
      2. water vapour
      3. dust and smoke
      4. all of these
   4. For photosynthesis, plants need
      1. nitrogen
      2. oxygen
      3. carbon dioxide
      4. none of these
   5. Main causes of air pollution are
      1. excessive burning of fuels
      2. burning of wood
      3. vehicles releasing smoke
      4. all of these
5. 5.

   Match the following.

   Column A	Column B
   1. Noble gases	a. Less than 1%
   2. Oxygen	b. Gills
   3. Nitrogen	c. Spiracles
   4. Fish	d. 21%
   5. Insects	e. 78%

    

6. 6.

   Write one word for the following.

   1. A thick blanket of air.
   2. A gas that supports burning.
   3. A gas that does not support burning.
   4. Special organs for respiration in fish.
   5. The addition of harmful gases and substances in air.