RBSE Class 6 Science Important Questions Chapter 5 Separation of Substances

Rajasthan Board  RBSE Class 6 Science Important Questions Chapter 5 Separation of Substances Important Questions and Answers.

RBSE Class 6 Science Chapter 5 Important Questions Separation of Substances

Multiple Choice Questions

Question 1. 
If a solid substance is dissolved in water, the method used for separation is:
(a) Distillation 
(b) Evaporation
(c) Filtration 
(d) Decantation
Answer:
(c) Filtration 

 

Question 2. 
Scraps of iron can be separated from the mixture by the process of:
(a) Magnetic separation 
(b) Sedimentation
(c) Winnowing
(d) Sieving
Answer:
(a) Magnetic separation 

Question 3. 
The process of settling down of the heavy and insoluble particles of a solid mixed in a liquid is called as:
(a) Decantation 
(b) Sedimentation
(c) Winnowing 
(d) Sieving
Answer:
(b) Sedimentation

Question 4. 
Which of the following is a heterogeneous mixture?
(a) A salt solution
(b) A salt-pepper mixture
(c) Air
(d) A fizzy drink
Answer:
(b) A salt-pepper mixture

Question 5. 
The process of vapour converting into a liquid is called as:
(a) Condensation 
(b) Loading
(c) Winnowing 
(d) Evaporation
Answer:
(a) Condensation 

Question 6. 
In agriculture, winnowing precedes washing, but comes after:
(a) Handpicking 
(b) Threshing
(c) Sieving 
(d) Filtration
Answer: 
(b) Threshing

Fill in the Blanks

Question 1. 
Materials which contain two or more substances in any proportion are called ...................  
Answer:
mixture

Question 2. 
Mixtures are not ................... in appearance and composition.
Answer:
uniform

Question 3. 
Cereals like wheat and rice can be rid of stones and dead insects by the process of ................... 
Answer:
hand-picking

Question 4. 
The process in which a liquid changes into vapour is called ................... 
Answer:
evaporation

Question 5.
Tea. leaves are separated from the prepared tea with a ................... 
Answer:
strainer

Question 6. 
When seawater is allowed to stand in shallow pits, water gets heated by sunlight and slowly turns into ..................., through evaporation.
Answer: 
water vapour

State whether True or False

Question 1. 
Rock salt is an impure substance.
Answer:
True

Question 2. 
Filtration is used to make fruit juice.
Answer:
True

Question 3. 
A solution of salt in water can be evaporated to get back pure salt.
Answer:
True

Question 4. 
Salt is produced by the process of evaporation of pond water.
Answer:
False

Question 5. 
Winnowing always comes after handpicking and threshing.
Answer: 
True

Match the followings

Column I	Column II
1. Mixture	(a) gas into liquid
2. Solution	(b) removing nations
3. Winnowing	(C) separation of heavier and lighter components
4. Strainer	(d) more than one substance
5. Decanting	(e) not excess amount of solute
6. Evaporation	(f) muddy water purification
7. Condensation	(g) liquid into vapour
8. Filtration	(h) separating tea leaves from tea
9. Handpickirig	(i) salt in water
10. Saturated	(j) stone from mustard seeds

Answer: 

Column I	Column II
1. Mixture	(d) more than one substance
2. Solution	(i) salt in water
3. Winnowing	(C) separation of heavier and lighter components
4. Strainer	(h) separating tea leaves from tea
5. Decanting	(b) removing nations
6. Evaporation	(g) liquid into vapour
7. Condensation	(a) gas into liquid
8. Filtration	(f) muddy water purification
9. Handpickirig	(j) stone from mustard seeds
10. Saturated	(e) not excess amount of solute

Very Short Answer Type Questions

Question 1. 
What do you mean by a saturated solution?
Answer: 
Solution in which no more substance like sugar or salt can be dissolved at a given temperature is called a saturated solution.

Question 2. 
Which process is used to separate impurities from rice and pulses after washing them?
Answer: 
Sedimentation.

Question 3. 
Which method is usually used to separate small pieces of stones from pulses freshly brought from the stores?
Answer: 
Handpicking.

Question 4. 
What do you mean by a pure substance?
Answer: 
Those substances or materials that are made up of only a single kind of component are called pure substances.

Question 5. 
How are clay particles suspended in muddy water removed even after sedimentation and decantation?
Answer: 
The remaining clay particles are removed by the method of filtration.

Question 6. 
What do you mean by a solution? 
Answer:
A solution is a homogeneous mixture of two or more substances.

Question 7.
How is salt produced from seawater?
Answer: 
Salt is produced by the process of evaporation.

Short Answer Type Questions

Question 1. 
How does the solubility of a substance vary with temperature? 
Answer: 
The solubility of a substance generally ' increases with increase in temperature. This means that larger amount of a substance (e.g., sugar, salt) can be dissolved in a given amount of water on heating it (or raising its temperature). Similarly, the solubility of a substance decreases on lowering down the temperature (by cooling). This means that lesser amount of a substance will dissolve in a given amount of water on reducing its temperature.

Question 2. 
What do you mean by immiscible liquids? How are they separated?
Answer: 
Liquids that do not mix with each other is known as immiscible liquids. They can be separated by the process of decantation. For example - when oil is mixed with water, each substance forms a separate layer in the mixture. The upper layer can be removed by decantation.

Question 3. 
Define mixture and list some properties of mixture.
Answer: Material which contains two or more substances in any proportion is called mixture. Properties of mixtures:

• A mixture may be a solid, liquid or gas.
• The various substances which are present in a mixture are called their constituents.
• Mixtures may be homogeneous or heterogeneous in nature.

Question 4. 
What happens if a saturated solution of sugar is cooled to a lower temperature?
Answer: 
A solution is said to be saturated if it cannot dissolve more substance. Once the temperature drops, the water has a new saturation point and releases the sugar from it.

Question 5. 
Suppose your mother wants to remove pieces of vegetables' from a large quantity of soup. Find out how she can do that quickly? 
Answer: 
My mother can do it quickly by passing the soup through a sieve. The vegetable pieces being bigger will be left over the sieve, while soup will easily pass through it.

Question 6. 
Is it true that a substance can be pure or a mixture? Explain with the help of examples.
Answer: 
The substance may be pure or a mixture.

• A substance is said to be pure when there are no impurities present in it. For example - distilled water.
• A substance which is composed of two or more substances is called a mixture. For example - lemonade is a mixture of water and lemon.

Long Answer Type Questions

Question 1. 
Explain the use of each of the following methods:
(a) Sieving, 
(b) Winnowing, 
(c) Handpicking.
Answer: 
(a) Straining of tea leaves after making tea.
(b) Winnowing helps in the separation of husk or chaff from wheat grains or rice grains with the help of wind.
(c) Handpicking helps in the removal of large solid impurities from a mixture if present in fewer amounts. For example - removal of stones and sticks from pulses and rice.

Question 2. 
How will you separate a mixture of common salt, sand and iron filings?
Answer:

• In the separation process, first, we use the magnet to remove the iron filings.
• Distilled water is added to the mixture containing sand and salt placed in a beaker and stirred it well with a glass rod.
• The beaker is then left undisturbed for some time which allows the sand particles to settle down.
• The remaining liquid contains the dissolved salt which is slowly decanted and then filtered through a filter paper.
• The sand is allowed to dry in the presence of air to remove all moisture.
• The saltwater is heated to evaporate all the liquid in it. By this process, only the salt residue left behind. Hence, the mixture is separated.

Question 3. 
Write a short note on the types of threshing.
Answer: 
There are three main types of threshing:
(a) Manual Threshing: When the quantity is small, threshing is done by the people themselves. Small bundles of the harvested stalks are threshed or hit on a hard surface. This helps in separating the grains.
(b) Threshing by Animals: For larger quantities, threshing is done by using animals such as bullocks.
(c) Threshing Machine: For very large quantities of grains, threshing is done by threshing machines. It can be powered by electricity or fuels like diesel and has the advantage of saving both time and labour.