Separation of Substances - I

Option (3) is correct.

Option (3) is correct. 

Option (1) is correct.

Option (2) is correct.

Dirt, stone and husk are big enough to be easily separated from pulses, rice, etc. by handpicking. 

Impurities in wheat vary in size. On the commercial scale, impurities like husk and stones are removed before grinding wheat by pouring it on a slanting sieve. This removes the pieces of stones, stalk and husk that may still remain after threshing and winnowing. So, apart from winnowing, the two methods are threshing and sieving. 

Winnowing is a method in which the heavier particles are separated from the lighter ones due to the difference in their weight. Separation of husk from grains is done using this method. 

Salt is soluble in water but sand is not. Sand being heavier settles at the bottom and can be separated by filtering the mixture. Salt and water can be separated by evaporation as water will evaporate leaving the salt behind. The water vapours can be collected by condensation. So, the methods involved in separating the mixture of sand, water and salt are filtration, evaporation and condensation. 

If we keep on adding a substance to water then a state arrives, when no more solute can be dissolved in it. Such a solution is said to be saturated, though more solute in the same can be dissolved by heating the solution. 

A mixture of sugar, water and rice can be separated by the process of filtration, which will separate rice from the mixture; followed by evaporation which will separate water from sugar, leaving sugar behind. 

Muddy water can be purified by the process of sedimentation, followed by using alum, which removes the lighter impurities also. This water then may be chlorinated to kill any bacteria and to get pure water. 

Decantation is a method used to separate a mixture of two liquids which do not mix with each other, and form different layers. Oil being lighter stays at the surface and water remains at the bottom, therefore the two can be separated by decantation. 

Chalk powder is insoluble and salt is soluble in water. So, we will dissolve both the substances in separate test tubes. The one which gets dissolved will be salt and the other which is insoluble is chalk powder. 

Evaporation refers to the conversion of a liquid into vapor state. A mixture of sugar and water can be separated by evaporation as water can evaporate but sugar can not.  

Tea leaves are separated from liquid by using a strainer or sieve and the process is known as filtration.