Question

Four students took separately the mixture of sand, common salt and ammonium chloride in beakers, added water, stirred the mixture well and then filtered. They reported their observations as shown below.

Student	As residue	In the filtrate
I	Ammonium chloride	Sand Common salt
II	Common salt, Sand	Ammonium chloride
III	Sand, Ammonium chloride	Common Salt
IV	Sand	Ammonium chloride, Common salt

Who reported the observations in the correct order of the components as residue and in the filtrate ?
(1) I
(2) IV
(3) III
(4) II

Answer 1

Solid ammonium chloride directly converted to the gas phase, and can easily be separated out from the mixture as residue
Common salt dissolves in water and after evaporation, it can also be separated from the mixture as residue.
So ammonium chloride and common salt are categorized as residue while sand was left in the mixture as filtrate.
So, the observations made by student III were correct.

Hence, the correct answer is option 3.