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

Recall the form of latent heat to increase the temperature of melting ice. After some time, the temperature of both ice and water will be the same. There is no extra source of heat to increase the temperature of water.

Complete step by step answer:
We have been given that the water in the test tube is surrounded by melting ice. So, the temperature of ice is $0^\circ C$ as it is on the verge to become liquid water and the temperature of water is greater than $0^\circ C$.
After some time, the temperature of both water and melting ice will become greater than the initial temperature of melting ice and less than the initial temperature of water due heat transfer from melting ice. To freeze the water below $0^\circ C$, the heat released by the water should be absorbed by the ice. But since the temperature of both water and ice has become the same, there is nothing that can absorb the heat released by the water. Therefore, the water will not freeze.
To boil or steam the water, heat must be supplied to the water. As there is no external source of heat, the water will not boil or steam. Therefore, the option (C) and (D) is incorrect.

So, the correct answer is “Option A”.

Note:
To solve such types of questions the key is to remember every form of latent heat. There are different forms of latent heat: latent heat of fusion, latent heat of sublimation, latent heat of solidification. Whenever you encounter the problem finding the heat, use one of the forms of latent which suits the given situation.