Access to the AP 6th Class Science Guide 3rd Lesson Separation of Substances Questions and Answers are aligned with the curriculum standards.
Separation of Substances AP 6th Class Science 3rd Lesson Questions and Answers
Exercises
Question 1.
Why do we need to separate different components of a mixture ? Give two examples.
Answer:
1. In a mixture, there may be two to three components are present. In them some of them are useful and some are harmful for us.
2. To remove these harmful components from a mixture, we need to separate them.
- Example 1: Stone pieces from wheat, rice or pulses are picked out by hand.
- Example 2: Tea leaves are separated from the liquid with a stainer while preparing tea.
Question 2.
What is winnowing? Where is it used?
Answer:
- Winnowing is a method used to separate heavier and lighter components of a mixture by wind or by blowing air.
- This process is used by farmers to separate lighter husk particles from heavier seeds of grain.
Question 3.
How will you separate husk or dirt particles from a given sample of pulses before cooking?
Answer:
Husk or dirt particles can be separated by winnowing, being lighter they will fly away from pulses.
Question 4.
What is sieving? Where is it used?
Answer:
- Sieving is a process by which fine particles are separated from bigger particles by using a sieve.
- It is used in flour mill or at construction sites.
- In flour mills, impurities like husks and stones are removed from wheat.
- Pebbles and stones are removed from sand by sieving.
- How will you separate sand and water from their mixture?
Question 5.
How will you separate sand and water from their mixture?
Answer:
- We will separate sand and water by sedimentation and decantation method.
- First we leave this mixture for some time.
- After a few minutes, the sand which is heavier is settled down at the bottom.
- Then we will pour water into another container and the mixture will be separated.
Question 6.
Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Answer:
- Yes, we can separate the sugar from wheat flour by sieving.
- Due to difference in the size of the particles, sugar will remain on sieve and wheat flour will pass through it.
Question 7.
How would you obtain clear water from a sample of muddy water?
Answer:
1. We will obtain clear water from a sample of muddy water by the process of filtration.
2. A filter paper has very fine pores to filter the water.
3. A filter paper folded in the form of a cone is fixed in a funnel. The mixture is then poured on the filter paper.
4. Solid particles in the mixture do not pass through it and remain on the filter.
8. Fill up the blanks.
a) The method of separating seeds of paddy from its stalks is called ___________
b) When milk, cooled after boiling, is poured on to a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of ___________
c) Salt is obtained from seawater by the process of ___________
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 ___________
Answer:
a) threshing
b) filtration
c) evaporation
d) sedimentation and decantation
9. True or false :
a) A mixture of milk and water can be separated by filtration.
b) A mixture of powdered salt and sugar can be separated by the process of winnowing.
c) Separation of sugar from tea can be done with filtration.
d) Grain and husk can be separated with the process of decantation.
Answer:
a) False. We cannot separate the mixture of milk and water by filtration, because milk is completely soluble in water.
b) False. Winnowing process is used to separate heavier and lighter components of a mixture.
c) False. Sugar cannot be separated from tea by filtration because sugar is completely soluble in tea.
d) True.
Question 10.
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?
Answer:
- We should add ice to lemonade after dissolving sugar. Without ice, sugar dissolves easily in lemon juice because solubility depends on the temperature.
- When the temperature is high, then more sugar can be dissolved. After adding ice, it gets cool and less sugar will dissolve in it.
Suggested Projects And Activities
Question 1.
Visit a nearby dairy and report about the processes used to separate cream from milk.
Answer:
- The process of centrifugation is used to separate cream from milk.
- The milk is put in a close container in big centrifuge machine.
- When the machine is switched on, the milk is rotated at a very high speed in it’s container.
- Due to centrifugal force, the milk separates into cream and skimmed milk.
Question 2.
You have tried a number of methods to separate impurities like mud from water. Sometimes, the water obtained after employing all these processes could still be a little muddy. Let us see if we can remove even this impurity completely. Take this filtered water in a glass. Tie a thread to a small piece of alum. Suspend the piece of alum in the water and swirl. Did the water become clear? What happened to the mud? This process is called loading. Talk to some elders in your family to find out whether they have seen or used this process.
Answer:
- When we add (or) suspend a piece of alum to muddy water, Alum removes the suspended clay particles from water
- Alum helps to remove odour from water
- This process is called loading.
- People use this method during rainy season to purify the drinking water in olden days.
- Alum is safe to use externally and internally.
Activities
Activity-1
Study the following table and match each process with it’s purpose and the way separated components are used.
Why do we separate substances ?
| Separation process | Purpose for which we do the separation | What do we do with the separated components ? |
| 1) Separate stones from rice | a) To separate two different, but useful components. | i) We throw away the solid component. |
| 2) Churning milk to obtain butter | b) To remove non-useful components. | ii) We throw away the impurities. |
| 3) Separate tea leaves | c) To remove impurities or harmful components. | iii) We use both the components. |
Answer:
| Separation process | Purpose for which we do the separation | What do we do with the separated components ? |
| 1) Separate stones from rice | a) To remove impurities or harmful components. | i) We throw away the solid component. |
| 2) Churning milk to obtain butter | b) To separate two different, but useful components. | ii) We use both the components. |
| 3) Separate tea leaves | c) I remove non-useful components. | iii) We throw away the impurities. |
Activity-2.
How do you examine a sample of food grain and separate it from impurity ?
Answer:
- Bring a packet of food grain purchased from a shop to the classroom.
- Now, spread the grains on a sheet of paper.
Observations: We can find pieces of stone, husks, broken grains and particles of any other grain.
Method of separation: Now remove with your hand the pieces of stone, husks and other grains from it. This method is known as hand picking method.
Activity-3
Write an activity to show the method of winnowing.
Answer:
1. Take a mixture of dry sand with saw dust or powdered dry leaves.
2. Keep this mixture on a plate or newspaper.
3. Now, take the mixture in open ground and stand on a raised platform.
4. Hold the plate or sheet of paper containing the mixture at your shoulder height.
5. Tilt it slightly, so that the mixture slides out slowly.
Observations:
- Saw dust and dry leaves are blown away.
- Sand which is heavier settles down.
Method of separation of components :
- This method of separating components of a mixture is called winnowing. It is used to separate heavier and lighter components of a mixture by wind or by blowing air.
- This method is very commonly used by farmers to separate lighter husk particles from heavier seeds of grain.
Activity-4
Write an activity that show separation of powdered chalk with wheat flour in your class.
Answer:
1. Bring a sieve and a small quantity of a flour from home to the class. ?
2. Sieve the flour to separate any impurities in it.
3. Now, make a fine powder of chalk pieces and mix it with the flour.
4. Now, pass the mixture through the sieve which has small pores.
Observations: Finely powdered chalk will pass through the sieve, but flour will remain in the sieve only. Thus, we can separate the mixture.
Activity -5
Write an activity to separate mud and water from muddy water.
Answer:
1. Collect some muddy water from a pond or a river.
2. Let it stand for half an hour. Observe the water carefully and you will find sbme soil settle down at the bottom of water. We call this process sedimentation.
3. Even after sedimentation, we further purify it by filtration using cloth or filter paper. Cloth further separates the small particles, which are present in dirt water.
4. For, further purification, we use filter paper which has very fine pores which we cannot see with our eyes. They completely filter the mud from water. The solid particles of mud in the water remain on the filter.
Activity-6
Write an activity to the method of ‘Evaporation’ in your science lab. (OR) How do you demonstrate an experiment to separate salt from salt water ?
Answer:
1. Add two spoons of salt to water in a beaker. Salt is completely soluble in water and does not change the colour of the water.
2. We can separate the salt from salt water by heating.
3. On heating water evaporates while salt remains in the beaker.
4. We get salt in our home from the same method. Sea water contains salt. Salt industries get salt by evaporating them and supply our house after further purification. This process is known as ‘evaporation’.
Activity-7
Write an activity to separate salt and sand from a mixture. (OR)
Demonstrate an experiment to show the method of condensation.
Answer:
1. Take a mixture of sand and salt.
2. Keep the mixture in a beaker and add some water to it.
3. Leave the beaker aside for some time.
4. The sand is setting down at the bottom of the beaker. The sand can be separated by decantation or filtration.
5. The decanted water contains the salt which was there in the mixture at the beginning.
6. Now, we need to separate salt and water from the salt water. Transfer this liquid in to a kettle and close it’s lid.
7. Heat the kettle for sometime until you notice steam coming out of it.
8. Take a metal plate and some ice on it. Hold the plate just above the spout of the kettle as shown in figure. Let all the water in the kettle boil off.
Observations:
- When the steam comes in contact with the metal plates cooled with ice.
- It condenses and forms liquid water. The water drops that you observed filling from the plate, were due to condensation of steam.
Activity-8
Write an activity to prepare a saturated salt solution In your science lab.
Answer:
1. Take a beaker and pour half a cup of water in the beaker.
2. Add one tea spoonful of salt and stir it well, until the salt dissolves completely.
3. Again add another teaspoonful of salt to it and stir well.
4. Go on adding salt, one teaspoonful at a time and stir.
Observations:
- After adding a few spoons of salt, we can notice that some salt remains undissolved in the amount of water we have taken.
- This is called “saturated salt solution”.
Activity-9
Write an activity to show the affect of temperature on solubility of solids in liquids.
Answer:
1. Take some water in a beaker and mix salt in it, until it cannot dissolve any more salt.
2. Now, add some salt to this saturated salt solution and heat it.
Observations:
- The undissolved salt is dissolved in hot water.
- After cooling the solution, the salt appears to be settle at the bottom of the beaker.
Inference: This activity suggests that larger quantity of salt can be dissolved in water on heating.
Activity-10
Write an activity to prepare saturated solutions of sugar and salt and compare the results.
Answer:
1. Take two glasses and pour half a cup of water in each of them.
2. Add a teaspoon of salt (5 mg) to it and stir it. Go on adding salt, one teaspoon at a time, till the solution saturates.
3. Record the number of spoons of salt that dissolved in water in the given table.
4. Now repeat the same with sugar and note down your observations in the given table.
Observations:
- Salt is more soluble in water than sugar.
- We dissolve 7 spoons of salt (each spoon of 5 mg) in 100 ml of water.
- While after adding 4 spoons of sugar, (20 gm) in 100 ml of water.
| Substance | No. of spoons of substance that dissolved in water |
| Salt | 7 spoons (each of 5 mg) (35 mg/100 ml) |
| Sugar | 4 spoons (20 mg/100 ml) |
| Glucose | 18 spoons (91 mg/100 ml) |