Page 67 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

rate of movement increases
distance decreases

energy decreases
attractive force increases

rate of movement decreases
3. Spirit kept open in a watch glass disappears after some time.
Which among the following phenomena are responsible for
this?

a) sublimation b) distillation
c) evaporation c) diffusion
4. Which are the methods that can be used to separate the
components of a mixture made of common salt, ammonium
chloride and sand?
Write the methods in the order in which they are applied.
5. Many minerals are present in ordinary water.
a) Which is the method that can be used to remove the
minerals and obtain pure water?

b) In which type of mixtures is this method employed?
c) Water purified by this method is distilled water Write
two instances of its use.
6. From the following statements, tick ( ) those which apply to
solid substances alone.
Particles have little freedom of movement.
Distance between particles is very high

Particles remain very close to each other
Energy of particles is very high

Extended activities

1. Take a small wooden rectangular block and find its volume.
(volume = length x breadth x height).
Take a big measuring jar and fill three-fourth of it with water
and mark the water level. Then dip the block in water in the
jar. (To prevent floating, nails can be inserted in the block).
Mark the difference in the water level.

a) Is there any relation between the difference in the water
level and the volume of the block?
Basic Science VIII
66 66 Basic Science VIII