Chapter 5 – separation of subtances
ACTIVITY- 1 : To demonstrate handpicking.
Question 1- How will you separate rotten tomatoes from a basket of tomatoes?
Answer- By hand picking.
Question 2- How will you separate green grapes from black grapes?
Answer- By hand picking.
ACTIVITY- 2 : To demonstrate winnowing.
Question 1- What is the role of wind in winnowing?
Answer- Lighter particles of mixture are blown away by air in winnowing.
Question 2- Can you separate mixture of channa dal and moong dal by winnowing?
Answer- No.
ACTIVITY- 3 : To demonstrate sieving.
Question 1- Can you separate a mixture of salt and flour with sieve? Why or Why not?
Answer- No, because both have almost same size particles.
ACTIVITY- 4 : To demonstrate sedimentation & decantation.
Question 1- You are provided with a solution of chalk powder and water in a beaker. Keep the beaker undisturbed for some time. What will you observe? Name the process.
Answer- On keeping the beaker undisturbed chalk powder settles down at the bottom of beaker. This process is known as sedimentation.
ACTIVITY- 5 : To demonstrate filtration.
Question 1- Your father asked you to bring fresh orange juice from market. Do you observe the strainer used to separate pulp and seeds from the juice? Which strainer is best for this purpose? Whether tea strainer, filter paper, muslin cloth or strainer with large holes can be used for this purpose.
Answer- Yes. Tea strainer is best for separating pulp and seeds from the juice.
ACTIVITY- 6 : To separate salt from salt solution.
Question 1- Name the process involved in preparation of “Khoya” from milk?
Answer- Evaporation.
ACTIVITY- 7 : Separation of salt, sand and water from the mixture.
Question 1- Name the process by which water changes to vapours.
Answer- Evaporation.
Question 2- Name the process by which vapours changes to water?
Answer- Condensation.
EXERCISE
Question 1- Fill In The Blanks.
a). Filtration process is helpful in separating an insoluble solid from a liquid.
b). Small pieces of stones can be removed from rice by hand picking method.
c). A strainer is used to remove husk from flour.
d). The method in which stalks are beaten to separate the grains is called threshing.
e). Decantation is the process of pouring out the liquid present on top layer without disturbing the sediments below.
Question 2- Write True Or False.
a). Sieving is used when the component of mixture has different sizes. (True)
b). Process of converting liquid to vapours is called condensation. (False)
c). A mixture of salt and flour is separated by handpicking. (False)
d). Threshing is a process of separating grains from stalks. (True)
Question 3- Match The Column ‘A’ With Column ‘B’.
Column A Column B
a. Separating salt from water a. condensation (d)
b. Heavier particles settle down b. winnowing (c)
c. Separating different components
by blowing wind or air c. evaporation (a)
d. Conversion of vapour into liquid d. sedimentation (b)
Question 4. Choose The Correct Answer.
(i). Which method is used to separate heavier and lighter components in a mixture by wind?
a) Hand picking
b) Threshing
c) Sieving
d) Winnowing (✓)
(ii). Formation of water droplets on the outer surface of glass containing ice cold water is because of :
a) Evaporation of water from glass
b) Condensation of atmospheric water vapours. (✓)
c) Water that seeped out from glass
d) Evaporation of atmospheric water vapours.
(iii). You must have seen your mother taking out fine gravels from rice. Which method can be used to separate pebbles from rice?
a) Handpicking (✓)
b) Decantation
c) Evaporation
d) Sedimentation
(iv). We need to separate one substance from mixture because:
a) To separate two different but useful components
b) To remove undesirable substances
c) To remove harmful substances
d) All the above (✓)
Question 5- Very Short Answer Type Questions.
(i) Define sedimentation.
Answer- Process of settling down heavy particles of an insoluble solid in a liquid is known as sedimentation.
(ii) What is evaporation?
Answer- Evaporation is a process of converting a liquid into its vapour form.
(iii) For what purpose combine machine is used for?
Answer- For harvesting and threshing.
Question 6- Short Answer Type Questions.
(i) Give difference between evaporation and condensation.
Answer- Evaporation- Evaporation is a process of converting a liquid into its vapour form. For example: converting water into vapours.
Condensation- Condensation is a process of converting vapours into liquid form. For example: Formation of water droplets on the outer surface of glass containing ice cold water
(ii) Give difference between saturated solution and unsaturated solution.
Answer- Saturated solution- The solution in which no more solute (salt, sugar etc.) can be dissolved at a given temperature is called saturated solution.
Unsaturated solution- The solution in which more of solute can be dissolved at a given temperature is called unsaturated solution.
(iii) Explain different types of threshing.
Answer- (1) Manual threshing- By beating the stalks with sticks etc.
(2) Threshing by animals.
(3) Threshing by machines like combine.
Question 7- Long Answer Type Questions.
(i) Explain the following methods of separation.
a). Threshing.
b). Winnowing.
c). Sieving.
Answer- (a). Threshing- Threshing is a process of separation of grains from stalks. Threshing can be done manually, by animals or with machines like combine.
(b). Winnowing- Winnowing is a method to separate heavier and lighter components of a mixture by wind or by blowing air.
(c). Sieving- Sieving is a method to separate larger substance from smaller substances.
(ii) What is separation? Why do we need to separate different components of a mixture?
Answer- Separation is a process of separating different components of a mixture. Separation is done to remove undesirable and harmful substances and to obtain desirable components of mixture.
