Question

Which of the following applications is based on the principle of elevation in freezing point with decrease in external pressure?

• A. Cooking of food at high altitudes using pressure cooker.
• B. Addition of alcohol to water used as a coolant.
• C. Existence of ice above 0⁰C on mountain peaks.
• D. Survival of aquatic animals in cold countries in winter at below 0⁰C.

Answer 1

The correct option is C

Existence of ice above 0⁰C on mountain peaks.

The explanation for the correct option :

Option: (c) : The atmospheric pressure decreases with altitude and due to a decrease in pressure, the melting point increases. Thus, ice exists above 0⁰C on mountain peaks due to elevated melting points at low pressures.

The explanation for incorrect options

Option (a) : Cooking food at high altitudes using a pressure cooker uses the principle that the boiling point of water is lowered at low pressures, thus pressure cookers are used to maintain the pressure so that food can be cooked properly.

Option (b): Alcohol lowers the freezing point of the water preventing the water to freeze.

Option (d): In colder regions, only the top layer of the water bodies froze keeping the inside layers in liquid water that supports the survival of aquatic animals even at below 0⁰C.

Thus, the correct option is (c)