Question:
You are given two samples of water labelled as $A$ and ' $B$ '. Sample $A$ boils at $100^{\circ} C$ and sample ' $B$ ' boils at $102^{\circ} \mathrm{C}$. Which sample of water will not freeze at $0^{\circ} \mathrm{C}$ ? Comment.
Solution:
The standard boiling point temperature of water is $100^{\circ} \mathrm{C}$. Therefore, the sample v/ith boiling point $100^{\circ} \mathrm{C}$ represents the pure form of water. The sample with boiling point $102^{\circ} \mathrm{C}$ is impure. Please note that impurities always raise the boiling point temperatures of liquids and lower their freezing point temperature. Therefore, the sample ' $B$ ' will freeze before $0^{\circ} \mathrm{C}$.