Question

A piece of ice at ${{0}^{\circ }}C$ is put into a vessel containing water at ${{0}^{\circ }}C$.The ice will
a) melt
b) not melt
c) slightly melt
d) vanish in no time

Answer 1

Ice basically starts melting if it absorbs heat from its surroundings. Ice is in the form of solid water which is at 0 degree Celsius. If the ice cube is kept at a higher temperature then the ice will absorb heat and after absorbing a particular amount of heat i.e. latent heat of fusion it will start melting provided that the temperature is still above) degree Celsius. Hence from this data we can determine the answer to the above question.

Formula used:
$Q=mL$
$\Delta Q=mc\Delta T$

Complete step by step answer:
In order for ice to undergo a change in state, it has to absorb heat(Q) i.e. equal to $Q=mL$ where m is the mass of ice and L is the latent heat of fusion. Once ice has absorbed this amount of heat and subjected to more heat than it will start melting. The heat gained by anybody when subjected to increase in temperature is given by, $\Delta Q=mc\Delta T$, where m is the mass of the body, c is the specific heat capacity of the body and $\Delta T$ is the increase in temperature.
It is given in the question that the ice at zero degree Celsius is kept in a container of water at zero degree Celsius. Since the temperature of the ice and the water is the same we can imply $\Delta T=0$, a result of which there will be no exchange of heat between the ice and the water i.e. $\Delta Q=0$. Ice melts when it absorbs heat. But since there is no exchange of heat, the ice will not melt.

So, the correct answer is “Option B”.

Note:
It is to be noted that the change in temperature of the body is inversely proportional to the specific heat capacity. Ice has very low specific heat capacity. Hence even a small amount of heat is sufficient to melt ice. If the specific heat of ice was very large then the increase in the temperature of the ice would be minimal and hence it would have not easily undergone a change in state.