Methods of Separation in Everyday Life – Class 6 Science Chapter 9: Important Questions and Answers FREE PDF Download
FAQs on CBSE Class 6 Science Important Questions Chapter 9 - Methods of Separation in Everyday Life
1. Why is it necessary to separate substances from a mixture? Give an important example from daily life.
Separating substances is necessary for several reasons:
- To remove harmful or unwanted components.
- To obtain a pure and useful substance.
- To group components of a mixture for different uses.
2. For the upcoming CBSE Class 6 Science exam, explain the methods of handpicking, threshing, and winnowing.
These are important manual separation methods:
- Handpicking: This method involves manually picking out slightly larger impurities like stones, dirt, or other grains by hand. It is useful when the quantity of impurities is not very large.
- Threshing: This is the process of beating dried stalks of crops to separate the grains from the stalk. It is commonly done by farmers after harvesting crops like wheat or paddy.
- Winnowing: This method is used to separate heavier components from lighter ones using wind. For instance, farmers use winnowing to separate lighter husk particles from heavier wheat grains.
3. A student is asked to separate a mixture of sand and water. What are the two main processes they should use? Explain each step.
To separate a mixture of sand and water, the student should use sedimentation and decantation.
- Step 1: Sedimentation: The mixture is left undisturbed for some time. Since sand is heavier than water, it settles down at the bottom of the container due to gravity. This process is called sedimentation.
- Step 2: Decantation: After the sand has settled, the clear water from the top is gently poured into another container without disturbing the settled sand (sediment). This process of pouring out the liquid is called decantation.
4. Describe the complete step-by-step process required to separate a mixture of salt and sand. This is a frequently asked question.
To separate a mixture of salt and sand, you need to use more than one separation method. The steps are:
- First, add water to the mixture. The salt will dissolve in the water, but the sand will not.
- Next, use filtration to separate the sand. Pour the mixture through a filter paper; the insoluble sand will be left on the filter, while the saltwater solution passes through.
- Finally, use evaporation to recover the salt. Heat the saltwater solution until all the water turns into vapour, leaving the pure salt behind.
5. What is evaporation, and for which type of mixture is this method most suitable?
Evaporation is the process where a liquid turns into its vapour (gas) upon heating. This method is most suitable for separating a soluble solid that is dissolved in a liquid. The most common example is obtaining salt from seawater, where the water evaporates due to the sun's heat, leaving the salt crystals behind.
6. How can you separate a mixture of iron filings and sulphur powder without using water?
You can separate a mixture of iron filings and sulphur powder by using the method of magnetic separation. This works because iron is a magnetic material, while sulphur is not. By moving a strong magnet over the mixture, the iron filings will be attracted and stick to the magnet, leaving the non-magnetic sulphur powder behind.
7. Why can't filtration be used to separate dissolved salt from water? What method is appropriate instead and why?
Filtration cannot be used because when salt dissolves in water, it breaks down into particles so small that they can easily pass through the pores of a filter paper. Filtration only works for separating insoluble solids. The appropriate method is evaporation, as it removes the liquid (water) by turning it into vapour, leaving the dissolved solid (salt) behind.
8. What is the key difference between sedimentation and filtration when separating mud from muddy water?
The key difference is the effectiveness of separation. Sedimentation is a slower process where heavier mud particles settle at the bottom due to gravity, but very fine particles may remain suspended in the water. Filtration is a more efficient method where the entire mixture is passed through a filter, which physically traps even very fine, insoluble mud particles, resulting in much clearer water.
9. What is a saturated solution? As a HOTS (Higher Order Thinking Skills) question, how can you dissolve more substance into an already saturated solution?
A saturated solution is a solution in which no more solute (like salt or sugar) can be dissolved in the solvent (like water) at a specific temperature. To dissolve more solute into a saturated solution, you can increase its temperature. Heating the solution generally increases the capacity of the solvent to dissolve more solute.
10. Explain the principle behind using a sieve. Give two important examples where this method is used in daily life.
The principle of sieving is to separate solid particles of different sizes. A sieve has small holes or a mesh that allows smaller particles to pass through while retaining the larger ones. Two common examples are:
- Separating fine flour from lumps or bran in the kitchen.
- Separating pebbles and stones from sand at a construction site.
