What type of mixtures are separated by the technique of crystallisation?

Give an example each of a mixture that shows the following characteristics:
$(i)$ $A$ mixture of two coloured components.
$(ii)$ $A$ mixture of two volatile components with a boiling point difference of less than $25\ K$.
$(iii)$ $A$ mixture of a volatile and a non-volatile solid component.

$(i)$ Name the process or the separation technique you would follow to separate:
$(a)$ Dyes in black ink
$(b)$ Butter from cream
$(c)$ Ammonium chloride and common salt
$(d)$ Iron filings and sand
$(ii)$ State the principle used in separation by centrifugation.

How can we obtain pure copper sulphate from an impure sample?

Enumerate any two differences between simple distillation and fractional distillation.

Jessica saw her mother rotating a milk churner in a container of milk. She was surprised and asked her mother why she was doing that. Her mother smiled and explained that she was separating cream from milk,which would be used in various dishes.
$(a)$ What kind of qualities are shown by Jessica's mother?
$(b)$ How is cream easily separated from milk by a milk churner?