Question

Which of the following processes enable pure water to be obtained from seawater?
I.filtration
II.distillation
III.evaporation

A.I and II only
B. I and III only
C.II and III only
D.I, II and III

Answer 1

Hint: We know that there are many processes of separation of mixtures. To separate soluble components from a mixture, many methods such as evaporation, condensation, distillation are used.

Complete step by step answer:

Let’s discuss all the methods given in the options in detail.

Filtration is the method which is used in separation of insoluble components of a mixture. For example, soil and water. Here, soil is insoluble in water. So, we can separate soil from water by using the filter paper. The water passes through the filter paper and soil particles cannot and thus soil and water separated.

Evaporation is the method in which particles at the surface of the liquid gain enough energy to overcome the forces of attraction of liquid particles and changes to liquid state.

Distillation is the method in which liquid is vaporized by heating and the vapors are condensed to form liquid.

Now, come to the question. Here, we have to choose the separation method used to get pure water from the seawater.

First method is filtration. We know that, filtration method is used to separate insoluble components from a mixture. But, in seawater salt is soluble in water. So, the filtration method is not used to obtain pure water from salt water.

Next method is evaporation. On supplying heat to the sea water, water got vaporized but the salt particles cannot. Thus, water gets separated from the salt particles. If we condense the vaporized water, pure liquid will be obtained.

Last method is distillation. In this method, sea water present in a flask is vaporized by heating. Then the vapors are condensed to form liquid. Thus pure water got separated from the salt. So, the distillation method is also used to obtain pure water from sea water.

So, the correct answer is Option C .

Note: Some methods used for separation of insoluble components from a mixture are filtration, sedimentation and decantation, winnowing, sieving etc. Hand picking is one of the common methods used to separate an undesirable solid from a solid-solid mixture.