CBSE Class 6 Science Separation Of Substances Worksheet Set 07

Multiple Choice Questions

Question 1 Husk is separated from heavier seeds of grain
a. winnowing
b. Hand picking
c. sieving
d. None of the above
Answer : A

Question 2 Which of the following properties can affect dissolution of sugar in water?
a. Quantity of Sugar
b. Temperature
c. Type of water
d. Amount of sugar dissolved
Answer : B and D

Question 3 Which technique is used to purify dirty water?
a. Centrifugation
b. Evaporation
c. Sedimentation
d. Decantation
Answer : C

Question 4 Four mixtures are given below
(i) Kidney beans and chick peas
(ii) Pulses and rice
(iii) Rice flakes and corn
(iv) Potato wafers and biscuits Which of these can be separated by the method of winnowing?
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (iii) and (iv)
Answer : D

Question 5 A solution is said to be _______ if it cannot dissolve more of the substance in it.
a. Saturated
b. Unsaturated
c. Homogeneous
d. Heterogenous
Answer : A

Question 6 Statement A: A mixture of cement and pebbles can be separated by using the sieve with small pores
Statement B: A sieve with small pores will allow only small cement particles to pass through and will hold back the pebbles
a. Statement A is true only
b. Statement B is true only
c. Both are false
d. Both are true
Answer : D

Question 7 A mixture of salt, sand, oil and water is given ,which of these sequence can be used to separate salt
a. Decantation -> Filtration -> Evaporation
b. Filtration -> Evaporation -> Condensation
c. Filtration -> boiling ->Decantation
d. None of the above
Answer : A

Very Short questions/answers

Question 1: There are very few pure elements or compounds around us. Most substances are mixtures. True or false.
Answer : True, most of the substances around us exist in the mixed state and not as pure elements or compounds.

Question 2: The constituents of all mixtures are uniformly spread throughout the mixtures. True or false?
Answer : False, the constituents of a heterogeneous mixture are not uniformly spread throughout the mixture.

Question 3: Is a solution of sugar in water homogeneous or heterogeneous?
Answer : In case of a sugar solution, the sugar is distributed uniformly in the water. Thus, sugar solution is a homogeneous solution.

Question 4: Name one property of a compound that remains fixed and can be used to test if the compounds has impurities in it.
Answer : The melting point and boiling point are two properties of a compound that can be used to test its purity as they remain fixed

Question 5: We have to separate a mixture into its constituents because only pure compounds are useful to us. Mixtures are not of much use. True of false?
Answer : False, mixtures are also very useful to us. For example, the air we breathe is also a mixture of gases.

Question 6: Can a mixture of sawdust and water be separated by sedimentation and decantation?
Answer : Sedimentation and decantation cannot be used to separate sawdust from water because sawdust is not heavier than water. Sedimentation and decantation can only be used to separate an insoluble solid from a liquid if the solid is heavier than the liquid.

Question 7: Which method gives a better separation of an insoluble solid from a liquid−sedimentation and decantation, or filtration?
Answer : An insoluble solid can be separated from a liquid more efficiently by filtration. Filtration can separate out solids that are also lighter than the liquid and it is faster since, liquid need not be left to stand.

Question 8: Name the method which is used to speed up sedimentation.
Answer : The method used to speed up sedimentation is known as loading.

Question 9: Which separation method is used to separate wheat grains from chaff?
Answer : Wheat grains are separated from chaff using the process of winnowing.

Question 10: Name the method used to obtain salt from sea water.
Answer : Salt is obtained from sea water by evaporation of sea water.

Question 11: Which method will you use to get a pure liquid from a solution containing several soluble solids in the liquid?
Answer : Distillation can be used to get a pure liquid from a solution containing several soluble solids in the liquid.

Question 12: Which apparatus is used to cool the liquid vapours during distillation?
Answer : A Liebig's condensor is used to cool liquid vapours during distillation.

Question 13: Which apparatus is used to separate two immiscible liquids?
Answer : Two immiscible liquids can be separated using a separating funnel.

Question 14: The method that can be used to separate a liquid from a mixture of miscible liquids with different boiling points is ___________ distillation.
Answer : The method that can be used to separate a liquid from a mixture of miscible liquids with different boiling points is fractional distillation.

Question 15: Solubility of most solids in water increases with rise in temperature. True or false?
Answer : True. The solubility of most solids in water increases with rise in temperature.

Question 16: Can water dissolve liquids and gases also?
Answer : Yes, water can dissolve liquids such as alcohol or milk. It can also dissolve gases such as oxygen, nitrogen etc

1) Fill in the blanks _____

a. The method of separating mixture into its component by hand is called a ________.
Answer: Handpicking
In simple words: Handpicking is picking out unwanted solid particles by hand from a mixture.

Exam Tip: Use handpicking only when quantities are small and impurities are visibly different.

b. __________ is the method of separting husk from grains using wind.
Answer: Winnowing
In simple words: Winnowing uses wind or blowing air to separate lighter husk from heavier grain seeds.

Exam Tip: Remember that winnowing relies on the difference in weight between components.

c. The process of settling down of a solid at the bottom of liquid is called a _________.
Answer: Sedimentation
In simple words: Sedimentation occurs when heavier insoluble particles settle down at the bottom of a container.

Exam Tip: Sedimentation is usually followed by decantation to separate the liquid.

d. A substance that dissolves in liquid is called a ____________.
Answer: Solute
In simple words: The substance that gets dissolved in a solvent is called a solute (e.g., salt or sugar).

Exam Tip: Solute plus solvent makes a solution.

e. The mixture of a solute and a solvent is called a _____________.
Answer: Solution
In simple words: A homogeneous mixture formed when a solute dissolves completely in a solvent is a solution.

I Water is called a universal solvent because ____
(a) It can dissolve very few solid.
(b) It cannot dissolve any substance in it.
(c) It can dissolve only liquids.
(d) It can dissolve many solids, liquids and gases.
Answer: (d) It can dissolve many solids, liquids and gases.
Water dissolves a wide variety of substances, earning it the term universal solvent.
In simple words: Water can dissolve a large number of different materials.

Exam Tip: Universal solvent refers to water's exceptional ability to dissolve polar and ionic substances.

II A solution is said to be saturated if _____
(a) It can dissolve more of the substance in it.
(b) It cannot dissolve more of the substance in it.
(c) It can be filtered.
(d) It becomes very sweet.
Answer: (b) It cannot dissolve more of the substance in it.
A saturated solution has reached its maximum capacity to dissolve solute at that temperature.
In simple words: No more solute can be dissolved in a saturated solution.

Exam Tip: Heating a saturated solution can sometimes allow it to dissolve more solute, forming a supersaturated solution.

III The most convenient method for separating husk (bhusoa) from grain is___
(a) Decantation
(b) Handpicking
(c) Filteration
(d) Winnowing
Answer: (d) Winnowing
Winnowing is specifically used to separate lighter husk particles from heavier grains using wind.
In simple words: Wind blows away the light husk while heavy grains fall straight down.

Exam Tip: Farmers commonly use winnowing outdoors on windy days.

IV A mixture of coconut oil and water can be separated by _____
(a) Filteration
(b) Decantation
(c) handpicking
(d) Evaporation and condensation
Answer: (b) Decantation
Oil and water are immiscible liquids that form separate layers, which can be separated by carefully pouring out the top layer (decantation) or using a separating funnel.
In simple words: Since oil floats on water, the top layer can be poured off.

Exam Tip: Decantation is ideal for separating immiscible liquids of different densities.

V Peanuts are reparated from a mixture of pulses and rice by _______
(a) Winnowing
(b) Filteration
(c) Sieving
(d) handpicking
Answer: (d) handpicking
Peanuts are large enough to be easily picked out by hand from pulses and rice.
In simple words: Large components like peanuts are easily removed manually.

Exam Tip: Handpicking is best for large-sized impurities or components.

3. Coin one word for the following ___
a. The process of converting a liquid into its vapour __________.
Answer: Evaporation
In simple words: Changing liquid into gas or vapor is evaporation.

Exam Tip: Evaporation takes place at any temperature below the boiling point.

b. A substance that settles down at the bottom of a liquid __________.
Answer: Sediment
In simple words: The heavy solid material that settles at the bottom is called sediment.

Exam Tip: Do not confuse sediment (the solid) with sedimentation (the process).

c. A solution in which no more solute can be dissolved at a given tempoerature ___________.
Answer: Saturated solution
In simple words: A solution holding the maximum possible dissolved solute is saturated.

d. The process of converting water vapour into water drops. ___________.
Answer: Condensation
In simple words: Turning gas back into liquid is condensation.

Exam Tip: Condensation is the reverse of evaporation.

4. Label the flollowing diagram and Name the process method ___
A -
B -
C -
D -
Method -
Answer:
A - Filter paper cone
B - Funnel
C - Residue / Filter paper
D - Filtrate (Clear liquid)
Method - Filtration
In simple words: The diagram illustrates filtration using filter paper, funnel, and beaker.

Exam Tip: In filtration, insoluble solid remains on the filter paper as residue, and clear liquid passes through as filtrate.

5. Answer the following _
i. Is milk a mixture?
Answer: Yes, milk is a mixture of water, fat, proteins, lactose, and minerals.
In simple words: Milk contains multiple components combined together physically, making it a mixture.
Exam Tip: Emulsions like milk are liquid-in-liquid colloidal mixtures.

ii. Can filteration be used to seperate the components of milk.
Answer: No, filtration cannot separate the dissolved and colloidal components of milk because fat globules and proteins pass through or remain suspended uniformly.
In simple words: Standard filter paper cannot separate milk components because they are too fine or dissolved.
Exam Tip: Centrifugation is used instead of filtration to separate cream from milk.

iii. What is the process of removal of the clear liquid layer without disturbing the settled solid called ?
Answer: Decantation
In simple words: Pouring out clear liquid without disturbing the sediment is called decantation.
Exam Tip: Always use a glass rod to pour liquid gently during decantation.

6. Mention the method / process involve against the pictures _

a. 1 ......................................................
Answer: Sieving
In simple words: Sieving is used to separate particles of different sizes using a sieve.
Exam Tip: Sieving separates fine flour from bigger bran particles.

b. 2 ......................................................
Answer: Winnowing
In simple words: Winnowing uses wind to blow away lighter husk from grains.
Exam Tip: Heavy grains fall down vertically while light husk is blown away.

c. 3. a) ....................................
b) ....................................
Answer:
a) Evaporation
b) Condensation
In simple words: Water evaporates into steam and then condenses back into liquid water.
Exam Tip: This process combination (distillation method principle) is used to obtain pure water from a solution.

d. 4 a) ....................................
b) ....................................
Answer:
a) Sedimentation
b) Decantation
In simple words: Impurities settle down (sedimentation), and clear liquid is poured out (decantation).
Exam Tip: Sedimentation and decantation are sequential steps used for muddy water purification.

I) Fill in the blanks :

1. The argemone oil can cause _________________________disorders.

2.The choice of the method of separation depends upon the __________________ and ________________________ of the components of a mixture.

3. In ____________________process heavier grains are separated from lighter husk by wind.

4. Pebbles can be separated from the sand by the process of _________________

5. In a solution , the _______________________ solids settles down at the bottom by sedimentation.

6. The process of increasing the sedimentation by adding chemicals is called _______________________

7. The clear liquid obtained after filtration is called as__________________________

8. The solids left on the filter paper after filtration is known as ___________________

9. A __________________________solution cannot dissolve more of the substances at a given temperature.

10. The reappearance of excess dissolved substance from the solution on cooling is called ___________________________

II) Name the following :

1. The process by which butter separated from curd.

2. Chemicals used for loading or increasing sedimentation.

3. The method for separating a soluble solid from its solution.

4.The process by which pure salt separated from impure salt.

5. Diseases caused by bacteria ion water.

6. Method for separating paneer from curdled milk.

7. The gas used for killing micro organisms in water.

8. The method for separating two immiscible liquids.

III) True or False :

1. Stones can be separated from rice by winnowing .

2. Mixture of wheel flour and pulses can be separated by sieving.

3. In a solution the soluble solids will settle down.

4. Mixture of water and oil can be separated by filtration.

5. The water vapour changes to water by condensation.

6. Different amounts of soluble substances dissolve in fixed amount of water.

I. Fill in the blanks

1: Sand can be separated from water by the process of _________

2: Common salt is obtained from sea water by the process of __________

3: Husk is separated from rice by the process of ___________

4: Stones can be separated from rice by the process of _________

5: Grains can be separated from stalks by _____________

6: To separate tea leaves from tea we use a _________

II. Answer in one word

1: Name the method used to separate pebbles or stones from sand.
_______________________.

2: Name the method used to separate oil from water.
_______________________.

III. Define the following

1: Threshing 2: Handpicking 3: Filtration 4: Saturated solution

IV. Distinguish between

1: Evaporation and condensation.

2: Sedimentation and decantation.

V. How is common salt obtained from the sea water? Explain.