Answer:
The answers are:
1) Latent heat of fusion
2) Heat is released
3) The process is endothermic
Explanation:
(1) The amount of energy required to freeze one kg of a substance is called latent heat of fusion.
(2) In a process, if heat is absorbed, the change in enthalpy for the substance is positive.
In a process, if heat is released, the change in enthalpy for the substance is negative.
The enthalpy of freezing for water is -6.02 kJ/mol. Heat is released as the enthalpy is negative.
(3) A positive value for enthalpy of vaporization indicates that the process is endothermic.
An exothermic process is one in which energy is released. The enthalpy for the process is negative.
An endothermic process is one which energy is absorbed. The enthalpy for the process is positive.
