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

(N/A) $solution$ is a homogeneous mixture of two or more substances.
$(i)$ Tincture of iodine: Solute is $iodine$ and solvent is $alcohol$.
$(ii)$ Polluted air: Solute is $pollutants$ (like $SO_2$, $NO_2$, dust) and solvent is $air$ (mixture of gases).
$(iii)$ Soda water: Solute is $CO_2$ and solvent is $water$.
$(iv)$ Dilute hydrochloric acid: Solute is $HCl$ and solvent is $water$.