Question

The flow diagram shows how a student extracted pure, dry salt from rock salt. Choose the word that completes the flow diagram.

(A) Evaporation
(B) Condensation
(C) Freezing
(D) Distillation

Answer 1

Hint : Salt comes out of the ground in the form of rock salt when mined. Rock salt is usually a mixture of solid rock and salt. The extraction of pure and dry salt from rock salt takes place in several steps. To solve the word that completes the flow diagram, first write down the process of extraction and fill the correct word.

Complete Step By Step Answer:
The rock salt is crushed using the mortar and pestle. Then the crushed rock salt is put in a vessel and water is added to it. The mixture is then stirred so that the crushed rock salt dissolves in it. Now, the mixture is filtered. The mixture which comes through the filter paper should be clear. A part of this liquid is put in an evaporating basin and then it is heated. Some powder is left in the evaporating basin after heating. This powder is the required pure, dry salt. We can observe that the order of the processes to obtain pure, dry salt from rock salt is: crushing, dissolving, filtration and evaporation.
Therefore, option A is the correct answer.

Note :
Rock salt is a mineral that contains sodium chloride and also other minerals and impurities. Most of these contaminants can be removed using two simple purification methods: filtration and evaporation. But still, some impurities will remain in it, many of them will have been removed simply by using the difference in solubility in water, by applying heat to remove volatile compounds and by mechanical filtration.