Which of the following is an element?

How can we obtain a coloured component (dye) from blue/black ink?

The 'sea-water' can be classified as a homogeneous as well as heterogeneous mixture. Comment.

Which of the following will show Tyndall effect? Why?
$(a)$ Salt solution
$(b)$ Milk
$(c)$ Copper sulphate solution
$(d)$ Starch solution.

$(a)$ What is the effect of temperature on the solubility of a solid in a liquid?
$(b)$ Why is it possible to distinguish the particles of solute from those of solvent in a suspension?

What would you observe when
$(a)$ a saturated solution of potassium chloride prepared at $60\,^{\circ}\text{C}$ is allowed to cool to room temperature.
$(b)$ an aqueous sugar solution is heated to dryness.
$(c)$ a mixture of iron filings and sulphur powder is heated strongly.