What is the sequence of steps for separating a mixture of ammonium chloride, sand, and common salt?
A.Sublimation, adding water, filtration, and evaporation
B.Evaporation, adding water, filtration, and sublimation
C.Filtration, evaporation, sublimation, and adding water
D.Evaporation, sublimation, adding water, and filtration

Hint: We know various processes to separate a mixture. But first, you have to isolate the substance which is sublimating. Secondly, make a solution of the remaining substances with water. Then filter out the bulky solid particles which do not dissolve using a strainer.

Complete answer:
Sublimation is the process in which a solid substance gets converted into a gaseous state without going through the liquid phase. The transition is directly from solid to vapour.
We know that ammonium chloride is a sublimating substance. The process of sublimation begins by heating the mixture of ammonium chloride. An inverted funnel is placed over the container that has the ammonium chloride mixture. The other end of the funnel is blocked by a cotton plug to avoid the escape of ammonium chloride vapours. As the container is heated ammonium chloride sublimes and forms vapours which rise and cool down in the upper part of the funnel. The condensed vapours are collected as ammonium chloride crystals. Thus, ammonium chloride is isolated from the mixture using Sublimation.
Second Step- Adding water
After removal of ammonium chloride salt and sand have to separate. Adding water to them will dissolve the salt and result in the formation of a salt solution.
Third Step- Filtration
The sand is insoluble in water and is filtered out from the salt solution using a strainer. The sand particles are collected separately.
Fourth step- Evaporation
Now the only salt solution is left of the mixture. The salt is obtained by evaporating the water. The heat will evaporate the water as vapours and salt crystals will be left behind.
Final answer: Correct option: A) Sublimation, adding water, filtration, and evaporation.

Note:
Ammonium chloride has to be heated at a proper temperature. Excessive heating may not produce the desired vapours. Also, you might think that sand particles can be filtered out first. But as Ammonium chloride is present in the solution it also might get strained along with the sand. So, sublimation is the correct first step.