While discussing about solutions in class you invite one
student to dissolve a substance in water. After adding
certain amount of the substance, it starts appearing at
The solution becomes saturated
The substance starts freezing
Water starts freezing
ne solution becomes unsaturated
Answers
Explanation:
The process of beating harvested crops to separate grains from stalk Threshing
2. Separation of insoluble solids suspended in a liquid by allowing them to settle down Sedimentation
3. The process of pouring out the clear upper liquid without disturbing the sediments Decantation
4. Changing of a liquid into gaseous form Evaporation
5. The substance that gets dissolved Solute
6. The substance in which the solute dissolves Solvent
7. The ability of a substance to dissolve in a given liquid Solubility
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Question 1:
Grains or seeds are separated form the stalk by
(a) hand-picking
(b) winnowing
(c) sieving
(d) threshing
ANSWER:
(d) threshing
Grains or seeds are separated from the stalk by beating harvested crops, and this process is called threshing.
Page No 46:
Question 2:
Winnowing is used to separate the grain from the
(a) solvent
(b) sediment
(c) stalk
(d) chaff
ANSWER:
(d) chaff
Threshed grains may contain seed coverings and tiny pieces of stem or leaves collectively called chaff, which can be separated by winnowing.
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Question 3:
Hand picking is preferred when
(a) the quantity of the mixture is small
(b) the unwanted substance is present in large quantities
(c) the unwanted substance can dissolve
(d) the size or colour of the unwanted substance is the same as the useful one
ANSWER:
(a) the quantity of the mixture is small
Hand-picking is preferred when the quantity of the mixture is small, the unwanted substance is present in smaller quantities, and the size, shape and colour of the unwanted substance are different from those of the useful one.
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Question 4:
Condensation takes place only when
(a) water vapour hits a cold surface
(b) water vapour hits a hot surface
(c) a hot surface hits a warm surface
(d) water is heated
ANSWER:
(a) water vapour hits a cold surface
Condensation is the process by which water vapour condenses to form a liquid, and this happens when water vapour hits a cold surface.
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Question 5:
Which of the following is soluble in water?
(a) Chalk
(b) Sugar
(c) Sand
(d) Wood
ANSWER:
(b) Sugar
Chalk, sand and wood can be filtered from water through filtration, but sugar cannot be filtered. Sugar is soluble in water and dissolves in it.
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Question 1:
Fill in the blanks with the correct words.
1. The particles of the insoluble solid should be .................. (bigger/smaller) than the holes in the filtering device.
2. Chalk and sand are .................. (soluble/insoluble) in water.
3. The substance in which the solute dissolves is called a .................. (solution/solvent).
4. The quantity of a substance that can dissolve in .................. (hot/cold) water is much more as compared to .................. (hot/cold) water.
5. Sugar in the .................. (powdered/solid) form dissolves first.
ANSWER:
1. The particles of the insoluble solid should be bigger than the holes in the filtering device.
(This is because the particles of the insoluble solid would remain in the filtering device if they are bigger than the holes of the filtering device, and the filtered substance will pass through the holes and get separated.)
2. Chalk and sand are insoluble in water.
(Chalk and sand are insoluble in water and can be separated by filtration.)
3. The substance in which the solute dissolves is called a solvent.
(A solute dissolves in a solvent to give a solution.)
4. The quantity of a substance that can dissolve in hot water is much more as compared to the quantity of the substance that can dissolve in cold water.
(Heating water increases the solubility of a solute in it.)
5. Sugar in the powdered form dissolves first.
(A powdered solute is more soluble than the solute in the crystal form.)