9. Methods of Separation in Everyday Life
Answers to in-text questions, activities and Let us enhance our learning. NCERT Curiosity, Class 6 Science (CBSE).
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Activities and In-text Questions
Yes. We can use sieving. Chana dal passes through the holes of a suitable sieve but puffed rice stays on it.
We can also use winnowing, because puffed rice is lighter.
The light peanut skins are blown away. The heavier peanuts stay behind.
Blowing air separates the heavier and lighter components.
She can switch on a fan or go outside where wind is blowing. Moving air will carry the light husk away.
No. All particles will pass through the holes. Sieving works only when one component is bigger than the holes.
Sweat contains salt. When the water in sweat evaporates, the salt is left behind as white patches.
Salt is left behind. The water evaporates. So salt can be separated from salt solution by evaporation.
Yes. Heat the salt solution and hold a cold plate above it. The water vapour condenses on the plate and can be collected. Salt is left in the dish.
Leave the mixture undisturbed. Oil forms a separate layer on top. Then gently pour out the oil. This is decantation.
Use a cloth folded into many layers (4 or more). More layers make the pores smaller. For very fine particles, a filter paper works better.
The mud particles do not pass through the filter paper. Mud stays on the filter paper as residue. Clear water collects in the flask as filtrate.
- Cut a plastic bottle into two. Turn the top part upside down like a funnel.
- Put a piece of cotton or cloth in the neck.
- Add layers of fine sand, then coarse sand and then small pebbles.
- Pour pond water slowly from the top. Clearer water collects below.
This water is clearer but not safe to drink. It must be boiled first.
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We can make paneer (chhena) from it. Heat the sour milk so that it curdles.
Then pour it through a muslin cloth. Paneer stays on the cloth. This is filtration.
A mixer (blender). It churns curd and separates butter.
| To remove a non-useful component | To use two different components |
|---|---|
| 1. Separating small stones from pulses 3. Taking out green chillies from dalia or poha 4. Taking out seeds from watermelon 7. Separating pebbles from sand 9. Separating oil from water | 2. Churning curd to obtain butter 5. Sorting sawdust and iron nails from building material 6. Picking marigold flowers from other flowers 8. Separating coconut pieces from rice flour 10. Separating salt from salt solution |
Some phrases can go in either basket if you give a good reason.
| Method | Description |
|---|---|
| Handpicking | Large particles are handpicked |
| Threshing | Beating stalks to remove grains |
| Winnowing | Lighter component of a mixture is separated by blowing air |
| Sieving | Difference in size of solid particles |
| Evaporation | Separate salt from seawater |
| Condensation | Conversion of water vapour into its liquid state |
| Sedimentation | Heavier particles settle down |
| Decantation | Separation of oil and water / pouring off the liquid |
| Filtration | Insoluble particles get filtered as residue |
| Churning | Extract butter from curd |
| Magnetic separation | Difference in magnetic properties |
Let us enhance our learning
(ii) Sorting
(iii) Cream from milk
(iii) Pore size
(i) Salt can be separated from salt solution by keeping it under the Sun. — True. The water evaporates and salt is left behind.
(ii) Handpicking should be used only when the quantity of one component is less. — True. Picking large amounts by hand takes too much time.
(iii) A mixture of puffed rice and rice grains can be separated by threshing. — False. It can be separated by sieving or winnowing. Threshing separates grains from stalks.
(iv) A mixture of mustard oil and lemon water can be separated by decantation. — True. Oil does not mix with water and forms a layer on top.
(v) Sieving is used to separate a mixture of rice flour and water. — False. Filtration is used. Sieving is used for solids of different sizes.
| Column I | Column II |
|---|---|
| (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 |
- When the solid particles are heavy and settle down quickly, like sand in water.
- When washing rice and pulses.
- When the quantity is large and a quick separation is enough.
- When a filter or strainer is not available.
Yes. Nasal hair works like a filter. It traps dust and germs from the air we breathe in. This is like filtration.
Masks are made of layers of cotton cloth or special fabric with very fine pores.
They act as a filter. They stop dust, droplets and germs from entering our nose and mouth.
Title: Clean Water for Father
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.