Q12. How can we separate oil and water from their mixture?
Oil floats on water and form separate layer. Separating funnel can be used to
separate the two.
Q13. Why are
we able to dissolve more solute in a solvent at high temperature?
Ans. We are able to
dissolve more solute in a solvent at high temperature because high temperature
facilitates dissolving reaction by providing energy to break bonds in the
Q14. Why sieving is not used to separate very small stones from
Sieving is not used to separate very small stones from rice grains because both
are of almost same size and both will pass through the holes of the sieve.
Q15. There are 3 beakers half filled with water. Now add 3 spoon
of sugar in first beaker, 5 spoon of sugar in second beaker and 7 spoon of
sugar in third beaker. Stir the solution of all three beakers. Which solution
is more saturated?
Q16. Define the following terms:
Handpicking is a method
used to separate larger impurities like pieces of dirt, stones etc. just by picking
them out with the help of hand from the mixture.
Threshing is a method of
separating grains or seeds from the stalks by some mechanical means such as by
beating with a flail or by the action of a threshing machine.
The process of conversion
of water into water vapor is called evaporation.
The process of conversion
of water vapor into its liquid form is called condensation.
A solution in which no
more solute (such as sugar or salt) can be dissolved in the given amount of solvent
(such as water) at a particular temperature is known as saturated solution.
A solution in which more
solute (such as sugar or salt) can be dissolved in the given amount of solvent
(such as water) at a particular temperature is known as unsaturated solution.
Decantation is the process
of removing liquid from mixture when heavier component settles down at the
bottom of container.
A mixture of soluble solid
in liquid is called solution.
Substance that is
dissolved is called solute.
The liquid in which the
solute dissolves is called solvent.
Strainer is a device with holes
punched in it or made of crossed wires for separating solid matter from a
Q17. What is winnowing? Where
is it used?
Winnowing is the method in which heavier components of the mixture are
separated from the lighter components such as chaff, dirt, etc. by dropping
mixture from height into the air. This method is used by farmers to separate
husk and other lighter impurities from grains.
Q18. Why do we
need to separate the components of a mixture for the following reasons:
To separate two different but useful
components from the mixture.
To remove non – useful components from the
To remove impurities or harmful substance
from the mixture.
To remove the unwanted impurities from the mixture.
To obtain pure substances by removing the