Question
How is common salt obtained from seawater?
✓
Answer
When seawater is allowed to evaporate in shallow pits, water gets heated by sunlight and changes into water vapour by the process of evaporation leaving behind impure solid salts. Now, the lumps of impure common salt are crushed to get powdered salt. The powdered common salt is dissolved in water to prepare a solution. Now the solution of common salt is filtered to remove insoluble impurities. The clear solution is evaporated by heating to remove the water content to obtain a concentrated solution of common salt. The hot and concentrated solution is allowed to cool. On cooling, crystallization takes place and crystals of pure common salt are obtained.
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S.N.
|
Objects
|
|
Materials
|
|
$1.$
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Book
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$A$
|
Glass
|
|
$2.$
|
Tumblar
|
$B$
|
Wood
|
|
$3.$
|
Chair
|
$C$
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Paper
|
|
$4.$
|
Toy
|
$D$
|
Leather
|
|
$5.$
|
Shoes
|
$E$
|
Plastic
|
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→|
|
$COLUMN\ I$
|
|
$COLUMN\ II$
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|
$a$
|
Oil mixed in water
|
$i$
|
Sieving
|
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$b$
|
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|
$ii$
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Hand picking
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$c$
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$iii$
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Decantation
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$d$
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$iii$
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Magnet
|
|
$e$
|
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$iv$
|
Evaporation
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S.No.
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Column $A$
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S.No.
|
Column $B$
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|
$(a)$
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Cell
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$(i)$
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Allows electricity to pass through it.
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$(b)$
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Battery
|
$(ii)$
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|
$(c)$
|
Conductor
|
$(iii)$
|
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|
|
$(d)$
|
Insulator
|
$(iv)$
|
Glows when electricity passes in it.
|
|
$(e)$
|
Switch
|
$(v)$
|
A device which produces electricity.
|
|
$(f)$
|
Bulb
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$(vi)$
|
Is a path of electricity.
|
|
$(g)$
|
Filament
|
$(vii)$
|
Does not allow electricity to pass.
|
|
$(h)$
|
Circuit
|
$(viii)$
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A combination of cells.
|
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