Q26. How can
we convert a saturated solution into an unsaturated solution?
Ans. We can convert a
saturated solution into an unsaturated solution in the following ways:-
by heating the solution
by adding more solvent to the solution
Q27. How do
we get salt from sea water?
Ans. The salt can be
obtained from sea by the process of evaporation.
Sea water is collected in
shallow pits and heat of the sun slowly turns water into water vapor
and in few days through evaporation, the water evaporates completely leaving
behind solid common salt.
must have often noticed that sky becomes clear after the first rain. Explain
Ans. Rain drops attach
themselves to dust particles suspended in air, make them heavy and bring them down
to the earth that is why sky becomes clear.
between homogeneous and heterogeneous mixtures? Give an example of each.
Ans. Difference between
homogeneous and heterogeneous mixture
1. ‘homo’ means same
1. ‘hetero’ means
2. It has uniform
2. It has non uniform
3. It can’t be separated
3. It can be separated physically
4. Examples of
homogeneous mixtures are: salt in water, sugar in water.
4. Examples of
heterogeneous mixtures are: water and sand, oil and water.
should the size of the pores in a sieve depend upon?
Ans. The size of the pores
in a sieve depends upon the size of the substance to be separated and the
impurities of the mixture.
are colloids? Give few examples of colloids that you see in your daily life.
Ans. A colloid is mixture
where at least two types of substances that are not as small as a solution and
not as large as a suspension are mixed together. Each substance retains its own
properties. Examples: whipped cream, milk, butter, gelatin, jelly, muddy water,
plaster, colored glass, and paper.
Q32. What is
the importance of threshing to the farmers?
essence of threshing is separation of a cereal grain from the shaft. Threshing
is done after harvesting of the crops. This may be carried out in the field or
on the farm, by hand or with the help of animals or machines.
Q33. What is
the function of candles in home water filters?
candle filters are simple devices made out of clay and used to filter drinking
water in order to removes cloudiness, suspended materials and pathogens.