How does a cube of ice help to cool cup chocolate that is too hot drink?

* Heat Transfer: Ice is at a much lower temperature than the hot chocolate. When the ice is placed in the hot chocolate, heat energy flows from the warmer chocolate to the colder ice. This transfer of heat energy causes the chocolate to lose its heat and cool down.

* Melting: As the ice absorbs heat from the chocolate, it starts to melt. This melting process also absorbs heat, further contributing to the cooling of the chocolate.

* Conduction: There is some direct heat transfer through the physical contact between the ice and the chocolate. The ice absorbs heat from the chocolate through its surface.

In short: The ice acts as a heat sink, absorbing heat from the hot chocolate and lowering its temperature until it reaches a more palatable level.