Methods of Separation in Everyday LifeClass 6 Science NCERT Solutions
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Q1Let us enhance our learning
What purpose does handpicking serve in the process of separation?
(i)
Filtration
(ii)
Sorting
(iii)
Evaporation
(iv)
Decantation
Solution
Handpicking serves the purpose of (ii) Sorting.
Reason: The chapter states that handpicking is done 'on the basis of differences in size, colour and shape of the particles' to remove unwanted components or to select desired ones, which is essentially sorting.
Q2Let us enhance our learning
Which of the following substances are commonly separated using the churning method?
(i)
Oil from water
(ii)
Sand from water
(iii)
Cream from milk
(iv)
Oxygen from air
Solution
The churning method is commonly used to separate (iii) Cream from milk.
Reason: The chapter describes churning curd using a 'mathni' to separate butter, which is essentially cream, from buttermilk. This process separates the lighter butter (cream) that floats to the top.
Q3Let us enhance our learning
Which factor is usually essential for the filtration?
(i)
Apparatus size
(ii)
Presence of air
(iii)
Pore size
(iv)
Temperature of the mixture
Solution
The factor usually essential for filtration is (iii) Pore size.
Reason: The chapter explains that sieving 'allows the fine flour particles to pass through the holes of the sieve' and that 'pores in the cloth can be used as a filter'. It also mentions that 'a filter paper is one such filter that has very fine pores in it'. The size of these pores determines what particles can pass through and what particles are retained.
Q4Let us enhance our learning
State with reason(s) whether the following statements are True [T] or False [F]. Also, correct the False statement(s).
(i)
Salt can be separated from salt solution by keeping it under the Sun.
(ii)
Handpicking should be used only when the quantity of one component is less.
(iii)
A mixture of puffed rice and rice grains can be separated by threshing.
(iv)
A mixture of mustard oil and lemon water can be separated by decantation.
(v)
Sieving is used to separate a mixture of rice flour and water.
Solution
(i)
True [T]
Reason: The chapter explains that salt is obtained from seawater by keeping it in shallow pits and exposing it to sunlight and air, allowing the water to evaporate completely and leave behind the salt.
(ii)
True [T]
Reason: The chapter states, 'If the particles to be removed are present in small quantities and can easily be picked by hand, handpicking proves to be a convenient method.' This implies that handpicking is practical and efficient when the amount of the component to be separated (usually the undesirable one) is small.
(iii)
False [F]
Correction: A mixture of puffed rice and rice grains can be separated by handpicking or winnowing (if there is a significant density difference) or sieving (if there is a significant size difference). Threshing is used to separate grains from their stalks.
(iv)
True [T]
Reason: The chapter mentions that 'oil does not mix with water and forms a separate layer when left undisturbed for some time', and decantation is the method used to separate immiscible liquids like oil and water.
(v)
False [F]
Correction: Sieving is used to separate components of a solid-solid mixture that have different sizes. A mixture of rice flour and water is a solid-liquid mixture, which can be separated by filtration or evaporation (if the flour is dissolved or suspended and needs to be recovered from water, though flour is typically insoluble).
Q5Let us enhance our learning
Match the mixtures in Column I with their method of separation in Column II. Column I
(i)
Gram flour mixed with black gram
(ii)
Chalk powder mixed with water
(iii)
Corn mixed with potatoes
(iv)
Iron powder mixed with sawdust
(v)
Oil mixed with water Column II
(a)
Handpicking
(b)
Magnetic separation
(c)
Decantation
(d)
Sieving
(e) Filtration
Solution
(i)
Gram flour mixed with black gram (d) Sieving
(ii)
Chalk powder mixed with water (e) Filtration
(iii)
Corn mixed with potatoes (a) Handpicking
(iv)
Iron powder mixed with sawdust (b) Magnetic separation
(v)
Oil mixed with water (c) Decantation
Q6Let us enhance our learning
In what situations would you use decantation instead of filtration to separate solids from liquids?
Solution
Decantation is used instead of filtration to separate solids from liquids in situations where:
- The solid component is insoluble and significantly heavier than the liquid, allowing it to settle quickly at the bottom (sedimentation).
- A complete separation of the solid is not critically required, or a quick, initial separation is sufficient before further processing.
- The solid particles are relatively large and settle well, making it easy to pour off the liquid without disturbing the settled solid.
- Filtration equipment, such as a filter paper or a fine strainer, is not readily available.
Q7Let us enhance our learning
Can you relate the presence of nasal hair to any separation process?
Solution
Yes, the presence of nasal hair can be related to the filtration process. Similar to how a filter paper or a piece of cloth with fine pores separates impurities, nasal hair acts as a natural filter. It traps dust particles, pollen, and other larger impurities present in the air we breathe, preventing them from entering our respiratory system. This helps in purifying the air before it reaches the lungs.
Q8Let us enhance our learning
During the COVID-19 pandemic, all of us wore masks. Generally, what material are they made of? What is the role of these masks?
Solution
During the COVID-19 pandemic, masks were generally made of materials such as cloth (like cotton or synthetic fabrics), non-woven fabrics, or specialized filter materials.
The role of these masks is to act as a filter. They create a physical barrier with fine pores that help to trap and block the passage of small particles, including dust, pollen, and respiratory droplets (which may contain viruses). This prevents these particles from being inhaled by the wearer or expelled by an infected individual, thus reducing the spread of airborne contaminants.
Q9Let us enhance our learning
A mixture containing potatoes, salt and sawdust has been given to you. Outline a stepwise procedure for separating each component from this mixture.
Solution
To separate potatoes, salt, and sawdust from a mixture, the following stepwise procedure can be used:
- Handpicking: First, separate the large pieces of potatoes from the mixture by handpicking them, as they are easily visible and distinct in size and shape.
- Dissolving in water: Add water to the remaining mixture of salt and sawdust. Stir the mixture well. The common salt will dissolve completely in the water, forming a salt solution. The sawdust, being insoluble in water and lighter, will float on the surface.
- Decantation/Skimming: Carefully skim off the floating sawdust from the surface of the salt solution. Alternatively, if the sawdust forms a distinct layer, it can be gently decanted.
- Evaporation: Heat the remaining clear salt solution. As the water evaporates, it will leave the solid common salt behind in the container.
This procedure allows for the separation of potatoes, sawdust, and salt effectively.
Q10Let us enhance our learning
Read the following story titled 'Intelligent Leela' and tick the most appropriate options. Provide a suitable title of your choice for the paragraph. Leela was working in the farm with her father when she realised that they left their drinking water at home. Before her father felt thirsty/hungry, she went to the nearby pond to fetch some water/grains. After obtaining some water in the container, she noticed that the water was muddy and fit/unfit for drinking. To purify the water, she kept it for some time and then she filtered/churned the muddy water using a piece of paper/muslin cloth. Leela, then, cooled/boiled the water for about 10 minutes in a covered pan. After cooling/boiled, she filtered/churned it again and made it fit/unfit for drinking. She served this water to her father while having food, who blessed her and appreciated her efforts.
Solution
Leela was working in the farm with her father when she realised that they left their drinking water at home. Before her father felt thirsty, she went to the nearby pond to fetch some water. After obtaining some water in the container, she noticed that the water was muddy and unfit for drinking. To purify the water, she kept it for some time and then she filtered the muddy water using a piece of muslin cloth. Leela, then, boiled the water for about 10 minutes in a covered pan. After boiling, she filtered it again and made it fit for drinking. She served this water to her father while having food, who blessed her and appreciated her efforts.
Suitable Title: Leela's Water Purification