Separation of Substances
I Answer the following in two sentences:-
1.
Why do we need to separate component of a mixture? Give examples.
Ans: a) To separate harmful
or non – useful substances that maybe mixed with it
b) To separate even useful components if we need to use them separately
Ex: Milk or curd is churned to separate the butter.
- Grain is separated from stalks, while harvesting
2.
What is winnowing? Where is it used
Ans: Winnowing is method of separating components of a mixture. It is used to separate heavier and lighter components
of a mixture by wind or by blowing air. This method is commonly used by farmers
to separate lighter husk particles from heavier seeds of grain
3.How
will you separate husk or dirt particles from a given sample of pulses before
cooking.
Ans:We need to wash the pulses with water, husk or dirt particles being
lighter keep floating in water and pulses grain will settle down, so we can
easily remove them. Then, water with impurities can be removed by decantation.
4.What
is sieving? Where is it used ?
Ans: Sieving
is a process by which fine particles are separated from the bigger particles by
using sieve. It is used in flour mill or at a construction site. In flour mill,
impurities like husks & stones are removed from wheat, Pebble and stones
are removed from sand by sieving.
5.How
will you separate sand and water from their mixture?
Ans:We will separate sand & water by using sedimentation and decantation
method First we have to leave this mixture for some time After some time, the
sand which is heavier settles down at the bottom. After that we pour the water
into another container and the mixture will be separated
6.Is
it possible to separate sugar mixed with wheat flour? If yes, how will you do
it?
Ans:Yes, sugar can be separated from wheat flour by sieving. Due to
difference in the size of particles, sugar will stay on sieve and wheat flour
will pass through it.
7.How
would you obtain clear water from a sample of muddy water?
Ans:We will obtain clear water from a sample of muddy water by the process
of Alteration. A filter paper is on such filter that has very Fine pores in it,
A filter paper folded in the form of a cone is fixed in a funnel. The mixture
is then poured on the filter paper, solid particles in the mixture do not pass
through it and remain on the filter.
8.Lemonade
is prepared by mixing lemon juice and sugar in water, you wish to add ice to
cool it. Should you add ice to the lemonade before or after dissolving sugar?
In which case would it be possible to dissolve more sugar?
Ans:We should add ice after dissolving sugar because the dissolving power of
water decreases with decrease in temperature, so if we add ice Before
dissolving sugar, less amount of sugar will be get dissolved.
II.Fill up the
blanks:
a. The method of separating seeds of paddy from its stalks is called Threshing.
b.
This process of separating cream from milk is an example of Filtration.
c.
Salt is obtained from seawater by the process of Evaporation
d. Impurities settled at the bottom when muddy water was kept overnight in a bucket, The clear water was then poured off from the top. The process of separation used in this example is called Sedimentation and decantation.
III .True or False?
a.
A mixture of milk and water can be separated by Alteration (False)
b.
A mixture of powdered salt and sugar can be separated by the process of
winnowing. (False)
c.
Separation of sugar from tea can be done with filtration. (False)
d. Grain and husk can be separated with the process of decantation. (False)
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