Final answer:
The enthalpy of fusion of helium is 10.0 J/mol^-1 at its normal melting point. Whether the process is reversible or not depends on the conditions under which it occurs.
Step-by-step explanation:
The enthalpy of fusion is the amount of heat required to change one mole of a substance from the solid state to the liquid state. In the case of helium, the enthalpy of fusion is 10.0 J/mol^-1 at its normal melting point. Whether the process is reversible or not depends on the conditions under which it occurs.
If the enthalpy of fusion is measured under conditions where the process can be easily reversed, then it is considered a reversible process. However, if the conditions are such that the process cannot be easily reversed, then it is considered an irreversible process. Without further information, it is not possible to determine if the melting of helium is a reversible process or not.