Available Answers

1. 1.

   Tick (√) the correct options:

   1. The gas present in maximum amount in air is _______________.
      1. nitrogen
      2. carbon dioxide
      3. argon
      4. oxygen
   2. The amount of water vapour present in air is called _______________.
      1. humidity
      2. smoke
      3. oxygen
      4. dust
2. 2.

   Tick (√) the correct options:

   1. Aquatic plants and animals use _______________ to respire.
      1. dissolved oxygen
      2. dissolved carbon dioxide
      3. dissolved nitrogen
      4. dissolved argon
   2. When it rains heavily, earthworms come out of the soil because _______________.
      1. they like rain
      2. no air is left in the soil for them
      3. no food is left in the soil for them
      4. none of these
3. 3.

   Tick (√) the correct options:

   1. Which of the following lives in the soil?
      1. crocodile
      2. earthworm
      3. squirrel
      4. dog
   2. Balance of oxygen and carbon dioxide in air is maintained by _______________.
      1. plants
      2. animals
      3. both (a) and (b)
      4. none of these
   3. Burning of fuels produces _______________.
      1. fog
      2. smoke
      3. smog
      4. rain
   4. Which of the following is a clean fuel?
      1. CNG
      2. coal
      3. diesel
      4. kerosene oil
4. 4.

   Fill in the blanks:

   1. Air is used by all organisms for _______________.
   2. Moving air is called_______________.
   3. Air is a _______________ of gases.
   4. _______________ proved that air is a mixture of gases.
   5. _______________ is used to draw water from tube wells.
5. 5.

   Match the following:

   Column A	Column B
   1. Nitrogen	(a) interdependent in nature
   2. Oxygen	(b) carbon dioxide
   3. Photosynthesis	(c) decreases on heating
   4. Windmill	(d) 21% of air
   5. Plants and animals	(e) run flour mills
   6. Solubility of air in water	(f) 78% of air

    

6. 6.

   Name the gas that supports burning.