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

The teacher instructed three students $A$,$B$ and $C$ respectively to prepare a $50\%$ (mass by volume) solution of sodium hydroxide $(NaOH)$. $A$ dissolved $50\,g$ of $NaOH$ in $100\,mL$ of water,$B$ dissolved $50\,g$ of $NaOH$ in $100\,g$ of water while $C$ dissolved $50\,g$ of $NaOH$ in water to make $100\,mL$ of solution. Which one of them has made the desired solution and why?

Identify the solute and the solvent for the following mixtures:
$(a)$ Tincture of iodine
$(b)$ Soda water
$(c)$ Sugar solution
$(d)$ Polluted air
$(e)$ Dilute hydrochloric acid

Smoke and fog both are aerosols. In what way are they different?

Explain why particles of a colloidal solution do not settle down when left undisturbed,while in the case of a suspension they do.

You are given two samples of water labelled as $A$ and $B$. Sample $A$ boils at $100\,^{\circ}C$ and sample $B$ boils at $102\,^{\circ}C$. Which sample of water will not freeze at $0\,^{\circ}C$? Comment.