Available Answers

1. 1.

   Give one word for the following:

   1. It is a natural source of water.	_ A _ _
   2. It is invisible but everywhere around us	_ I _
   3. About 71% of our planet is covered with it.	_ _ T _ _
   4. It protects you from the harmful rays of the sun.	_ T _ _ TO _ _ H _ _ E

2. 2.

   Match the following:

   Column I	Column II
   1. Exosphere	(a) Weather changes
   2. Stratosphere	(b) Fifth layer
   3. Troposphere	(c) Prevent meteoroids entry
   4. Mesosphere	(d) Ozone layer

    

3. 3.

   Name the components of air using the hints given.

   1. ______________ Cannot be used directly by plants.
   2. ______________ Constitute 21 % of air.
   3. ______________ Filled in weather balloons.
   4. ______________ Helps green plants make food.
4. 4.

   Write true or false for the following statements.

   1. Air exerts pressure only in downward direction.
   2. Air occupies space but has no weight.
   3. Air is colourless and odourless.
   4. Air has a sweet taste.
5. 5.

   Fill in the blanks with appropriate words.

   1. ______________ present in air is essential for burning.
   2. ______________ of air helps to fill ink in a fountain pen.
   3. ______________ air helps sailing of boats.
   4. Astronauts carry ______________ for breathing in space.
6. 6.

   Categorise the following impurities into soluble and insoluble impurities.

   sand

   salt

   clay

   vegetable material

   microbes

   gases