Define the term $solution$. Identify the solute and solvent in the following solutions:
$(i)$ Tincture of iodine
$(ii)$ Polluted air
$(iii)$ Soda water
$(iv)$ Dilute hydrochloric acid

What is the effect of temperature on the solubility of solids in liquids?

Calculate the mass of water and mass of glucose required to make $250 \, g$ of $40 \%$ solution of glucose.

Write your observations when the following processes take place:
$(a)$ An aqueous solution of sugar is heated to dryness.
$(b)$ $A$ saturated solution of potassium chloride prepared at $60^\circ C$ is allowed to cool at room temperature.
$(c)$ $A$ mixture of iron filings and sulphur powder is heated strongly.
$(d)$ $A$ beam of light is passed through a colloidal solution.
$(e)$ $Dil. HCl$ is added to the mixture of iron and sulphur.

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

Which of the following are homogeneous in nature?
$(i)$ ice $(ii)$ wood $(iii)$ soil $(iv)$ air