Question

To separate a mixture of iron fillings, sulphur powder and iron sulphide, which sequence of methods can be used ?

• A. Magnet, dissolve in ${\mathrm{CS}}_2$, filter, evaporation
• B. magnet, dissolve in water, filter, evaporation
• C. dissolve in water, filter, crystallize, decant
• D. magnet, filter, decant, crystallize.

Answer 1

The correct option is A

Magnet, dissolve in ${\mathrm{CS}}_2$, filter, evaporation

The explanation for the correct option:

(a) Magnet, dissolve in${\mathrm{CS}}_2$, filter, evaporation:

1. We are given a mixture of iron fillings, sulphur powder and iron sulphide. We have to separate the components of this mixture.
2. Firstly, we will use a magnet to separate iron fillings from the mixture. As we know that iron is a metal it will cling to the magnet.
3. Secondly, we will dissolve the sulphur powder and iron sulphide in carbon-disulphide.
4. Thirdly, we will use filter paper to separate iron sulphide and the filtrate.
5. Finally, we evaporate the filtrate to get sulphur powder.

The explanation for incorrect options:

Since the correct sequence of methods used to separate a mixture of iron fillings, sulphur powder and iron sulphide are first to use a magnet, dissolve in${\mathrm{CS}}_2$, filter, and then finally evaporation thus options (b), (c) and (d) are incorrect.

Hence, option (a) is the correct option.