CBSE Class 6 Science Advanced Chemistry Matter and Its Segregation Very Short Answer Questions Set 01

Fill in the Blanks

Question 1. A ___________ substance has only one kind of matter.
Answer:
Pure. A pure substance is made up of only one kind of matter.
In simple words: A pure substance is made of just one kind of particle.

Teacher's Note:
1. Gold and water are pure substances.
2. Contrast this with a mixture, which has more than one kind.

Question 2. The composition and properties of a __________ mixture is uniform throughout.
Answer:
Homogeneous. A homogeneous mixture looks the same in every part.
In simple words: Homogeneous means the same everywhere.

Teacher's Note:
1. Tea and salt solution are examples.
2. Say 'uniform' whenever you define this word.

Question 3. An ___________ is a homogeneous mixture of two or more metals.
Answer:
Alloy. Brass (copper and zinc) is an example.
In simple words: An alloy is a uniform mixture of metals.

Teacher's Note:
1. Alloys are made by melting the metals together.
2. Remember brass, bronze and steel as examples.

Question 4. Chalk powder added in water is an example of a ___________.
Answer:
Heterogeneous mixture. Chalk does not dissolve, so it is visible and settles on standing.
In simple words: Chalk in water does not mix evenly, so the mixture is heterogeneous.

Teacher's Note:
1. Insoluble solids in water form heterogeneous mixtures.
2. Shake it and wait: the chalk settles at the bottom.

Question 5. When the heavier component in a mixture settles after water is added to it, the process is called ___________.
Answer:
Sedimentation. The settled solid is the sediment.
In simple words: Sedimentation is the settling of heavy particles at the bottom.

Teacher's Note:
1. Sediment settles; decantation pours off the liquid above it.
2. Keep these two terms apart.

Question 6. Camphor is separated from common salt by ________.
Answer:
Sublimation. Camphor changes directly to vapour on heating, but common salt does not.
In simple words: Camphor turns straight into vapour when heated and salt stays behind.

Teacher's Note:
1. Only a substance that sublimes can be separated this way.
2. Iodine, naphthalene and ammonium chloride behave like camphor.

Question 7. ___________ (Grains/Leaves) can be separated from stalk using threshing.
Answer:
Grains. Threshing frees the grains from the stalks.
In simple words: Threshing shakes the grains out of the stalks.

Teacher's Note:
1. Leaves are not the target of threshing.
2. Threshing is the first step; winnowing comes after it.

Question 8. Corn is separated from husk by the process ____________.
Answer:
Winnowing. The wind blows the light husk away while the heavier corn falls down.
In simple words: Wind blows the husk away and the corn falls in a heap.

Teacher's Note:
1. Winnowing needs a difference in weight.
2. Do not confuse it with threshing.

Question 9. Simplest way of separating broken rice from whole rice is ____________.
Answer:
Sieving. The broken pieces are smaller and pass through the holes of a sieve, while the whole grains stay on top.
In simple words: Broken rice is smaller, so it falls through a sieve.

Teacher's Note:
1. A sieve separates by size.
2. The same idea is used to separate pebbles from sand.

Question 10. A ______________ cannot dissolve more of a given substance at a given temperature.
Answer:
Saturated solution.
In simple words: A saturated solution is full; no more solute dissolves in it.

Teacher's Note:
1. Temperature matters: heat the solution and it can dissolve more.
2. The undissolved extra settles at the bottom.

True or False

Question 11. A mixture of milk and water can be separated by filtration. (True / False)
Answer:
False. Milk and water are both liquids and they mix completely, so a filter cannot hold either one back. Filtration separates an insoluble solid from a liquid.
In simple words: Filtration is only for insoluble solids in liquids.

Teacher's Note:
1. Both parts pass through filter paper together.
2. Ask: is any part an insoluble solid?

Question 12. A mixture of powdered salt and sugar can be separated by the process of winnowing. (True / False)
Answer:
False. Winnowing separates a light part from a heavy part using wind. Powdered salt and sugar are both fine and similar in weight, so wind cannot separate them.
In simple words: Wind cannot tell fine salt and sugar apart.

Teacher's Note:
1. Winnowing needs a clear difference in weight.
2. Salt and sugar mixtures are very hard to separate.

Question 13. Separation of sugar from tea can be done with filtration. (True / False)
Answer:
False. Sugar dissolves in tea. A dissolved solid passes through a filter with the liquid, so filtration removes only the tea leaves.
In simple words: Dissolved sugar goes through the filter with the tea.

Teacher's Note:
1. Dissolved solids need evaporation, not filtration.
2. The strainer removes only the leaves.

Question 14. Grain and husk can be separated with the process of decantation. (True / False)
Answer:
False. Decantation is pouring off a liquid from a settled solid. Grain and husk are dry solids and are separated by winnowing.
In simple words: Decantation is for liquids; grain and husk need winnowing.

Teacher's Note:
1. Pair each method with the state of the mixture.
2. Dry solids: handpicking, winnowing, sieving.

Match the Column

Teacher's Note:
1. Match the sure pairs first.
2. Loading is the only process that speeds up sedimentation.

Teacher's Note:
1. Check which parts are solid and which are liquid.
2. Winnowing is for a light and a heavy dry solid.

Very Short Answer Type

Question 17. How can you decide whether a substance is pure or not?
Answer:
A pure substance has only one kind of particle and has fixed properties, such as a definite melting point and boiling point.
If a substance has no fixed melting or boiling point, or can be split into parts by a physical method, it is a mixture.
In simple words: A pure substance has fixed properties; a mixture does not.

Teacher's Note:
1. Fixed melting and boiling points are the quick test.
2. Mixtures melt and boil over a range.

Question 18. What type of mixtures can be separated by filtration?
Answer:
Mixtures of an insoluble solid in a liquid, for example sand or chalk powder in water.
In simple words: Filtration separates a solid that does not dissolve from a liquid.

Teacher's Note:
1. The solid must be insoluble.
2. A tea strainer is a filter.

Question 19. Can a mixture of salt and sugar be separated by filtration?
Answer:
No. Both are solids, and both dissolve in water, so a filter cannot separate them.
In simple words: Filtration cannot separate two dissolving solids.

Teacher's Note:
1. Filtration works for insoluble solids in a liquid only.
2. Salt and sugar are both soluble.

Question 20. Name the apparatus that can be used to separate a mixture of mustard oil and water.
Answer:
A separating funnel.
In simple words: A separating funnel drains the lower layer and leaves the upper one.

Teacher's Note:
1. Oil floats on water, so water drains first.
2. It is used for immiscible liquids.

Question 21. What are aqueous solutions?
Answer:
Solutions in which water is the solvent are called aqueous solutions, for example salt dissolved in water.
In simple words: An aqueous solution is a solution made with water.

Teacher's Note:
1. Aqua means water.
2. Iodine dissolved in alcohol is not aqueous.

Ask Yourself

Question 22. What do you mean by pure substance?
Answer:
A pure substance is a material in which all the particles are of the same kind. It is either an element or a compound, for example gold or water, and it has fixed properties.
In simple words: A pure substance has only one kind of particle.

Teacher's Note:
1. Give one example of an element and one compound.
2. Pure substances cannot be separated by physical methods.

Question 23. Give two examples of solids which are soluble and insoluble in water.
Answer:
Soluble in water: salt and sugar.
Insoluble in water: sand and chalk powder.
In simple words: Salt and sugar dissolve in water; sand and chalk do not.

Teacher's Note:
1. Soluble solids disappear in water.
2. Insoluble solids stay visible or settle.

Question 24. Among the mixture of benzene and water, identify the bottom layer and top layer in a separating funnel.
Answer:
Benzene is lighter than water (density about 0.88 g per cm³ compared with 1 g per cm³), and the two do not mix.
Top layer: benzene. Bottom layer: water.
In simple words: Benzene is lighter, so it floats on the water.

Teacher's Note:
1. The lighter liquid always floats.
2. The lower layer is drained out first.

Question 25. Give an example of non-aqueous solution.
Answer:
Iodine dissolved in alcohol (tincture of iodine). The solvent here is alcohol, not water.
In simple words: A solution made with a solvent other than water.

Teacher's Note:
1. Sulphur in carbon disulphide is another example.
2. Name both the solute and the solvent.