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Class 6 Science: Methods of Separation in Everyday Life, 8 practice questions with answers

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These are 8 practice questions on the ninth chapter of the new NCERT Class 6 Science textbook, Curiosity, called Methods of Separation in Everyday Life. Each has a short answer and the textbook page it comes from. They cover choosing a method, threshing and winnowing, when a sieve can and cannot work, why filtering cannot get dissolved sugar back, sedimentation and decantation, choosing a filter, making gur, and pulling iron out with a magnet. For the properties of materials, see our Class 6 Materials Around Us guide. Try each question before you read the answer.

These questions are our own, drafted with AI help. Every fact was checked against the page it cites by a test script, but no practising teacher has reviewed them yet. If you find a mistake, please tell us.

What the chapter says you need

Facts from the NCERT textbook (Curiosity, Grade 6, Chapter 9, printed pages 163 to 181):

Choosing a method

Question 1. Which method of separation would you use for each? (a) Some iron paper clips have fallen into a box of crayons. (b) A bucket of water has sand in it, and you want most of the water back without the sand. (c) A bag of semolina (rava) has small hard lumps in it. (d) Small bits of chopped coriander are floating in a jug of buttermilk. (e) A few glass beads have fallen into a bowl of dry rajma.

Answer: (a) magnetic separation; (b) sedimentation, then decantation; (c) sieving; (d) filtration; (e) handpicking. (a) Iron is magnetic, so a magnet pulls the clips out and leaves the crayons. (b) Let the sand settle (sedimentation) and then tilt the bucket to pour off the water (decantation). (c) The lumps are bigger than the semolina grains, so a sieve with suitable holes keeps them back. (d) Pouring the buttermilk through a strainer, a filter, holds back the coriander bits, which do not dissolve, and lets the liquid through: filtration. (e) A few beads that look different from the beans can simply be picked out by hand. (Handpicking, page 164; sieving, page 167; sedimentation, decantation and filtration, pages 170 to 172; magnetic separation, pages 174 and 175.)

Question 2. (a) After the rajma harvest, a farmer dries the uprooted plants in the sun and then beats the bundles against the ground until the beans fall out of the dry pods. What is this step called, and why are the plants dried first? (b) What difference between the parts of a mixture does winnowing make use of?

Answer: (a) threshing; drying makes the beans come away more easily; (b) one part is heavier and the other lighter. (a) Beating harvested stalks so that the grains or seeds come off them is threshing. The chapter's farmers spread the stalks in the sun to dry before beating them; dry pods split and let go of the beans more easily than fresh, green ones (this reason goes a little beyond the chapter). (b) Winnowing uses wind or blown air to carry away the lighter part of a mixture while the heavier part falls nearby. (Threshing, page 164; winnowing, pages 165 and 166.)

Question 3. Some mustard seeds have got mixed with rajma beans. You want to separate them with a sieve. (a) Which of the two should pass through the holes? (b) What must be true of the size of the holes? (c) A jar of black mustard seeds has some yellow mustard seeds of exactly the same size mixed in. Can any sieve separate them? If not, what could you use instead?

Answer: (a) the mustard seeds; (b) bigger than a mustard seed but smaller than a bean; (c) no sieve can; picking out the yellow seeds by hand can, if there are only a few. Sieving works when the parts of a solid mixture have different sizes: the smaller particles pass through the holes and the bigger ones stay on the sieve. (a) Mustard seeds are much smaller than rajma beans, so they pass through. (b) The holes must let the small seeds through but hold back the beans. (c) Seeds of the same size all pass through the same holes, or all stay on the sieve, so sieving cannot separate them. They differ in colour, so if the yellow seeds are few, handpicking works. (Handpicking, page 164; sieving, page 167.)

Mixtures in water

Question 4. Ravi has spilled sugar into a glass of water and stirred it until it has all dissolved. He wants the sugar back, so he pours the sugar water through filter paper. (a) Why does no sugar stay on the paper? (b) Which method would get the sugar back, and how?

Answer: (a) dissolved sugar passes through with the water; (b) evaporation. (a) Filtration holds back only insoluble solid particles, the ones that are not dissolved. Once sugar has dissolved, it is spread through the water and passes through the pores of the filter paper with it, so nothing is left on the paper. (That sugar dissolves in water is general knowledge; the chapter shows salt dissolving in the same way.) (b) Leave the sugar water in a wide dish, for example in the sun, so that the water slowly evaporates and goes off as vapour. The sugar is left behind in the dish, just as salt is left behind when salt water dries. (Filtration, pages 170 to 172; evaporation, pages 167 to 169 and 177.)

Question 5. A bottle of water from the beach has sand in it. You let it stand, then carefully pour the water into a glass. (a) What are the two steps called? (b) Why is the water in the glass still not completely free of sand? (c) What could you do next?

Answer: (a) sedimentation and decantation; (b) decantation does not remove all of the solid; (c) filter it. (a) Letting the heavier, insoluble sand settle to the bottom is sedimentation; pouring off the water by tilting the bottle is decantation. (b) Decantation does not separate the solid completely: some fine particles still get carried over with the liquid, just as some tea leaves reach the cup when tea is only decanted. (c) Pass the water through a filter, such as a cloth or a filter paper, so that the remaining solid is caught. (Sedimentation, decantation and filtration, pages 170 and 171.)

Question 6. (a) To make coconut milk, grated coconut is soaked in water and squeezed. Poured through a wide-holed colander, the milk still has bits of coconut in it; squeezed through a thin cotton cloth, it comes out smooth. Why? (b) One glass holds orange juice with bits of pulp in it; another holds water with very fine ground coffee stirred in. Which can a kitchen strainer clean, and which needs filter paper?

Answer: (a) the cloth's pores are much smaller than the colander's holes; (b) the strainer for the orange juice, filter paper for the coffee. (a) A cloth has very small holes, or pores, between its woven threads, so it holds back the small bits of coconut that slip through the colander's wide holes, and only the milk passes. (b) Bits of orange pulp are fairly large, so the strainer's holes hold them back while the juice runs through. Fine coffee grounds are far smaller than a strainer's holes and would pass straight through, so a filter with even smaller pores, such as filter paper, is needed. (Filters with smaller and smaller pores, pages 170 to 172.)

Question 7. (a) Sand and common salt have been mixed together. Why can a sieve or handpicking not separate them easily? (b) In a village, freshly pressed sugarcane juice is boiled in wide open pans by the gur-makers until it turns into a thick, sticky mass that sets as gur. What leaves the pan during this, and what stays behind?

Answer: (a) the grains are too small and too alike; (b) water leaves as vapour; the sugary solids stay and become gur. (a) Sand and salt grains are both tiny and much the same size, so a sieve would let both through, and picking them out by hand would take far too long. (b) As the juice is heated, its water evaporates and goes off into the air as vapour, while the sugar and other solids dissolved in it cannot evaporate and are left in the pan. With less and less water, the juice thickens until only the solid gur remains, in the same way that salt is left behind when salt water is heated in a dish. (Only grown-ups who make gur do this; it is described here, not something to try.) (Sieving and handpicking, pages 164 and 167; evaporation, pages 167 to 169 and 177.)

Question 8. (a) At a hardware shop, a box of small iron screws spills into an open sack of rice. What is the quickest way to get the screws out, and what is the method called? (b) A magnet is passed over a tray holding an iron safety pin, a plastic button, an iron nail, a wooden bead and a rubber band. Which are lifted?

Answer: (a) run a magnet through the rice: magnetic separation; (b) the safety pin and the nail. (a) Iron is a magnetic substance, so it is attracted by a magnet, while rice is not. Moving a magnet through the rice pulls the screws out without sorting the grains by hand. Separating magnetic things from non-magnetic ones with a magnet is magnetic separation. (b) Only the two iron objects, the safety pin and the nail, are attracted; plastic, wood and rubber are not magnetic and stay on the tray. (Magnetic substances and magnetic separation, pages 174 and 175.)

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Sources

All opened and read on 2 November 2026. Page numbers are the printed page numbers of the textbook; printed page = PDF page + 162 for this chapter.

The facts are from the textbook pages above. The questions, answers and checks are our own. This guide is general information; follow your teacher and the textbook.

Practise with the worksheet: Methods of Separation, Class 6 worksheet. Printable, in English, Hindi and Marathi, with an answer key.