Topic outline

    • Separation of Substances

      Q1. State True/False

      i.             The property used in separating a mixture of two solid by winnowing is difference in weight. True

      ii.            The chemical used for loading is baking soda. False

      iii.          A mixture of milk and water can be separated by filtration. False

      iv.          A mixture of powdered salt and sugar can be separated by the process of winnowing. False

      v.           Separation of sugar from tea can be done with filtration. False

      vi.          Grain and husk can be separated with the process of decantation. False

      vii.        The method in which stalks are beaten to free the grain seeds is called threshing. True

      viii.       Sieving is used when the component of mixture are of different sizes. True

      ix.          The method of filtration is also used in the process of preparing cottage cheese in homes. True

      x.           When no more salt can be dissolved in the given amount of water at particular temperature, the solution is said to be unsaturated. False

      xi.          Centrifugation is used to separate cream from curd. True

      xii.        Hand picking can be used to separate cashew nuts from mixture of almonds and cashew nuts. True

      Q2. Fill in the blanks.

      i.             We can remove small stones from pulses before cooking by handpicking.

      ii.            The process of separating a liquid from solid sediment is called decantation.

      iii.          The method of separating seeds of paddy from its stalks is called threshing.

      iv.          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 filtration.

      v.           Salt is obtained from seawater by the process of evaporation.

      vi.          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 sedimentation and decantation.

      vii.        Hand picking method is used to separate stones from grains.

      viii.       Husk from wheat can be separated by decantation.

      ix.          Sieving is used to remove impurities and bran from the flour.

      x.           The two liquids that do not mix with each other can be separated by decantation.

      xi.          Salt is obtained from sea water.

      xii.        We see water drops under the plate that has been used to cover a container containing milk that has just been boiled. This is due to process of condensation.

      Q3. Write any two methods used for separation of substances.

      Ans. Hand picking and Threshing

      Q4. How can we separate sand from water?

      Ans. Sedimentation and Decantation


      Q5. Which method can be used to separate soil from mixture of soil and grains?

      Ans. Sieving


      Q6. Which method would you prefer to separate solid dissolved in liquid?

      Ans. Evaporation


      Q7. Which method farmers use to separate grains from bundles of stalk?

      Ans. Threshing


      Q8. Which method do you prefer for tea leaves from prepared tea?

      Ans. Filtration


      Q9 Filtration method is used to separate tea leaves from prepared tea. Which other method can be used?

      Ans. Decantation

      Q10. List various methods of separation of components from their mixtures.

      Ans. Some of the methods are: handpicking, winnowing, threshing, sedimentation, decantation, filtration, evaporation and condensation.


      Q11. The process of adding alum to water to fasten sedimentation is called loading. Why has this name been given to the process?

      Ans. It is because the suspended light particles become heavy on adding alum.


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