Salt can be recovered from its solution by evaporation. Suggest some other technique for the same?

Name the appropriate methods to separate the following:
$(i)$ Nitrogen from air
$(ii)$ Dye from blue ink
$(iii)$ Butter cream from milk
$(iv)$ Ammonium chloride from common salt

Which of the tubes in Fig. $(a)$ and $(b)$ will be more effective as a condenser in the distillation apparatus?

Crystallisation is a better technique than simple evaporation. Give one reason to justify the statement.

How can we separate a mixture of two immiscible liquids?

Name the technique used to separate:
$(i)$ Butter from curd,
$(ii)$ Salt from sea-water,
$(iii)$ Camphor from salt.