Answer:
12.3 kJ
Step-by-step explanation:
For a given substance, the molar heat of fusion basically tells you one thing from two perspectives
how much heat is needed in order to melt one mole of that substance at its melting point
how much heat must be removed in order to freeze one mole of that substance at its freezing point
It is very important to realize that the molar enthalpy of fusion will carry a positive sign when you're dealing with melting and a negative sign when you're dealing with freezing.