GSEB Class 6 Science Solutions Chapter 5 Separation of Substances

Question 1. Why do we need to separate different components of a mixture? Give two examples.
Answer: Among the various components of a mixture, many substances can be harmful or not useful for us. To take away these harmful or useless components, we need to separate them. Examples:
(a) Tea leaves are taken out from the liquid using a strainer when making tea.
(b) Small stones from wheat, rice, or pulses are picked out by hand.
In simple words: We separate mixtures to remove things that are bad or not needed, like taking out tea leaves from tea or stones from rice.

Exam Tip: When asked for examples, choose common everyday situations to illustrate the separation methods clearly.

Question 2. What is winnowing? Where is it used?
Answer: Winnowing is a process that helps separate heavier and lighter parts of a mixture by using wind or by blowing air. This method is utilized by farmers to separate lighter husk particles from heavier grain seeds.
In simple words: Winnowing uses wind to blow away light husks, leaving the heavier grains behind. Farmers often use this method.

Exam Tip: Remember that winnowing relies on the difference in weight between components, making it effective for separating husks from grains.

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 taken out by winnowing. Because they are lighter, these particles will fly away from the pulses when wind or air is used.
In simple words: Use winnowing to remove light husk and dirt from pulses; the wind blows them away because they are lighter.

Exam Tip: Winnowing is suitable for mixtures where one component is significantly lighter and can be carried away by air currents.

Question 4. What is sieving? Where is it used?
Answer: Sieving is a method where fine particles are separated from larger particles by passing them through a sieve. It is commonly used in flour mills or at construction sites. In flour mills, dirt like husks and stones are removed from wheat. Pebbles and stones are also removed from sand by sieving.
In simple words: Sieving separates big and small things using a net with holes. It's used to clean flour or separate stones from sand.

Exam Tip: Sieving is effective when the components of a mixture have different sizes, allowing smaller particles to pass through while larger ones are retained.

Question 5. How will you separate sand and water from their mixture?
Answer: We can separate sand and water by using the sedimentation and decantation method. Firstly, we leave this mixture alone for some time. After a while, the sand, which is heavier, settles down at the bottom. Following this, we can carefully pour the water into another container, and the mixture will be separated.
In simple words: Let the sand and water mixture sit so the sand sinks. Then, carefully pour the water away from the settled sand.

Exam Tip: Remember that sedimentation and decantation are best for mixtures of insoluble solids and liquids where the solid is denser than the liquid.

Question 6. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Answer: Yes, sugar can be separated from wheat flour by sieving. Because of the difference in particle sizes, the sugar will remain on the sieve while the wheat flour will pass through it.
In simple words: Yes, you can separate sugar from wheat flour by sieving because sugar particles are bigger than flour particles.

Exam Tip: This method works because sugar crystals are generally larger than flour particles, which highlights the importance of particle size in separation techniques.

Question 7. How would you obtain clear water from a sample of muddy water?
Answer: We can get clear water from a sample of muddy water through the process of filtration. A filter paper has very small holes in it. The steps for using a filter paper are shown in diagrams. A filter paper is folded into a cone shape and placed in a funnel. The muddy mixture is then poured onto the filter paper. The mud stays on the filter paper, and clean water drops into the beaker below.
In simple words: To get clear water from muddy water, we use filtration. We pour the muddy water through a special paper that catches the mud, letting only clear water pass through.

Exam Tip: Filtration is suitable for separating insoluble solids suspended in a liquid, where the filter medium traps the solid particles.

Question 8. Fill in the blanks:
(a) The method of separating seeds of paddy from its stalks is called ..........
(b) When milk, cooled after boiling, is poured onto 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
In simple words: The blanks are filled with the correct separation methods: threshing for paddy, filtration for cream, evaporation for salt, and sedimentation/decantation for muddy water.

Exam Tip: Understand the basic principles of each separation method to accurately fill in the blanks or identify the correct process for a given scenario.

Question 9. True/ 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 from the process of decantation.
Answer:
(a) False
(b) False
(c) False
(d) False
In simple words: All the statements are incorrect. Filtration doesn't separate milk and water, winnowing can't separate powdered salt and sugar, filtration won't separate dissolved sugar from tea, and decantation is not used for grain and husk.

Exam Tip: Carefully consider the properties of the substances in each mixture (solubility, particle size, density) to determine if the proposed separation method is appropriate.

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 after dissolving the sugar. When the liquid's temperature is high, more sugar can be dissolved easily. After mixing ice, the water gets cold, and it will take a longer time for the sugar to dissolve completely.
In simple words: Add ice after dissolving sugar. Warmer water dissolves more sugar quickly; cold water makes it take longer.

Exam Tip: Remember that solubility of most solids (like sugar) in liquids (like water) increases with temperature, so dissolving sugar in warm liquid is faster and allows for more sugar to be dissolved.