Question

A test tube containing some water is surrounded by melting ice (pure). Then, the water in the test tube will

A. not freeze into ice
B. freeze into ice
C. boil ultimately
D. become steam ultimately

Answer 1

The latent heat of fusion of ice is the amount of heat required to raise the temperature of 1 kg of ice at $0{}^\circ C$ completely to 1 kg of the water at the same temperature. The latent heat of fusion of ice is a constant value and is equal to $80\,{kcal}/{kg}\;$.

Complete step-by-step answer :
As per the statement, “A test tube containing some water is surrounded by the melting ice (pure).
This water surrounded by the melting ice cannot freeze completely into ice, as after some time the temperature of both, the water and that of the ice will reach a temperature of $0{}^\circ C$.

By the time the water starts to freeze (or starts to form the ice), the water releases heat.
As the water is surrounded by the ice, there will be no other source that can absorb the latent heat of fusion released by the freezing water.

The water will neither boil nor steam, as there is no external source of heat that might increase the temperature of the water to make it boil.

As, the water will not freeze not completely, thus option (A) not freeze into ice is correct.

Note : The things to be on your finger-tips for further information on solving these types of problems are: There are different forms of latent heat. They are Latent heat of fusion of ice, Latent heat of the steam and the Latent heat of solidification. So, these forms of latent heat should be used as per the given situations.