Page 13 - Understanding NCERT Science 09

• Take out approximately 10 mL of this 1.2.2 PARTICLES
solution and put it into 90 mL of clear
water.
• Take out 10 mL of this solution and
put it into another 90 mL of clear water.
• Keep diluting the solution like this 5 to
8 times.
• Is the water still coloured ?
Fig. 1.2: Estimating how small are the particles of
matter. With every dilution, though the colour • Put a drop of blue or red ink slowly
becomes light, it is still visible.
This experiment shows that just a few
crystals of potassium permanganate can
colour a large volume of water (about
1000 L). So we conclude that there must be
millions of tiny particles in just one crystal
of potassium permanganate, which keep
on dividing themselves into smaller and
smaller particles.
The same activity can be done using 2 ml
of Dettol instead of potassium permanganate.
The smell can be detected even on
repeated dilution.
The particles of matter are very small –
they are small beyond our imagination!!!!
1.2 Characteristics of Particles of
Matter
1.2.1 PARTICLES OF MATTER HAVE SPACE
BETWEEN THEM
In activities 1.1 and 1.2 we saw that particles
of sugar, salt, Dettol, or potassium
permanganate got evenly distributed in water.
Similarly, when we make tea, coffee or
lemonade (nimbu paani ), particles of one type
of matter get into the spaces between particles
of the other. This shows that there is enough
1.5), we can conclude the following:
space between particles of matter.
2 SCIENCE
Rationalised 2023-24
OF MATTER ARE
CONTINUOUSLY MOVING
Activity ______________ 1.3
• Put an unlit incense stick in a corner
of your class. How close do you have to
go near it so as to get its smell?
• Now light the incense stick. What
happens? Do you get the smell sitting
at a distance?
• Record your observations.
Activity ______________ 1.4
• Take two glasses/beakers filled with
water.
and carefully along the sides of the first
beaker and honey in the same way in
the second beaker.
• Leave them undisturbed in your house
or in a corner of the class.
• Record your observations.
• What do you observe immediately after
adding the ink drop?
• What do you observe immediately after
adding a drop of honey?
• How many hours or days does it take
for the colour of ink to spread evenly
throughout the water?
Activity ______________ 1.5
• Drop a crystal of copper sulphate or
potassium permanganate into a glass
of hot water and another containing
cold water. Do not stir the solution.
Allow the crystals to settle at the
bottom.
• What do you observe just above the
solid crystal in the glass?
• What happens as time passes?
• What does this suggest about the
particles of solid and liquid?
• Does the rate of mixing change with
temperature? Why and how?
From the above three activities (1.3, 1.4 and