Separation of Substances
1. Fill in the blanks:
(i) Name one method for separation of substances ________.
Ans: Winnowing
(ii) Separation of fine particles from bigger particles using a sieve ___________.
Ans: Sieving
(iii) Name on method used to separate sand and water _____________.
Ans: Sedimentation
(iv) Salt is obtained from seawater by a process known as __________.
Ans: Evaporation
(v) The process of separating cream from the milk is known as ___________.
Ans: Filtration
2. Define winnowing.
Ans: Winnowing is the process of separating heavy components from lighter components with the help of
wind.
3. What is sieving?
Ans: Sieving is the process of separating tiny particles from larger particles by the use of holes in a sieve.
4. Define threshing.
Ans: The term "threshing" refers to the process of removing grains from their stalks. The stalks are
beaten to liberate the grain seeds in this process.
5. Define sedimentation.
Ans: Sedimentation is the process in which heavier components settle down at the bottom of the
container. E.g. Water mixed with mud or sand.
6. Define decantation.
Ans: Decantation is the process of taking out clear water into a new container after sedimentation. The
water after decantation is clear but it is still not fit for drinking.
7. Define evaporation.
Ans: Evaporation is the process of converting water into water vapour.
8. Define condensation.
Ans: Condensation is the process of turning water vapour into liquid.
Example: Melting of ice.
9. Define saturated solution.
Ans: Saturated solution is a solution in which no more of a substance/solute can be dissolved.
10. Name 5 methods used for separating substances from their mixtures?
Ans: Five methods used for separating substances are:
• Winnowing
• Sieving
• Handpicking
• Threshing
• Decantation
11. Give one importance of separating substances from the mixtures.
Ans: It is important to separate substances from mixtures to obtain pure substances differently for various
purposes.
12. How do you separate sugar mixed with wheat flour?
Ans: The method of sieving is used to separate the sugar and wheat flour mixture. First, the mixture is
filtered through a sieve. Wheat flour particles will pass through, while the large sugar particles will be
trapped by the sieve.
13. Explain the method used to separate the sand and water from their mixture?
Ans: A combination of sedimentation and decantation is used to separate sand and water.
• A mixture of sand and water is taken in a glass/container and left for some time.
• Sand settles at the bottom of the container during this process because it is heavier. This is called
sedimentation.
• The clean water is then gradually moved to another container slowly leaving the sand in the
original container. This process is called decantation.
Fill in the Blanks
i.) When a heavier component of a mixture settles after adding water to it, this process is called
____.
ii.) The two liquids that do not mix with each other are called ____ liquids.
iii.) ____ is the opposite of evaporation.
iv.) Chalk powder can be separated from water by ____.
v.) ____ is the essential condition for winnowing.
Q1. What is the use of a strainer in separating substances?
Answer. A strainer is a type of sieve used to separate liquid from solid.
Q2. Which process is used to separate cream from curd?
Answer. Centrifugation.
Q3. List some of the materials that are used as filters.
Answer. Cotton, ceramic, filter cloth, and filter paper are some materials used as filters.
Q4. Which method can be used to separate salt from seawater?
Answer. Evaporation.
Q5. Which process is considered the opposite of evaporation?
Answer. Condensation.
Q6. How can husk be removed from wheat?
Answer. By winnowing.
Q7. Which method is used to separate stones from grains?
Answer. Handpicking.
Q8. Which method is used to separate two liquids that do not mix with each other?
Answer. Separating funnel.
Q9. Name the liquid that is known as the universal solvent.
Answer. Water.
Q10. What is the process for separating the heavier and lighter components of a mixture?
Answer. Winnowing.
Q5. What is unsaturated solution?
Answer. An unsaturated solution is one in which the solute can be dissolved at any fixed temperature.
Q6. When is the handpicking method used?
Answer. Handpicking method is used for separating undesirable components that differ in shape, size,
and colour and are present in small quantities.
Q8. What is a mixture?
Answer. A mixture is a mixture of two or more substances that do not react with one another. Examples
include sugar and water, sugar and sand, and so on.
Q9. Why is it necessary to separate substances from mixtures?
Answer. It is necessary to separate substances from mixtures in order to obtain pure substances for
various purposes.
Q11. Define handpicking.
Answer. Handpicking is a method of separation in which impurities in a mixture that differ from the useful
material are hand-picked and removed.
For example, stone pieces can be separated from wheat or rice by handpicking.
Q12. How will you separate a mixture of oil and water?
Answer. Since oil is lighter than water, it will float on it. Two distinct layers form, and oil is slowly allowed
to flow into another container, where it is separated from the water. This method to separate oil and water
is called a separating funnel.
