For a substance found in its melting point, if the enthalpy change needed for one mole of the substance to melt is ΔH = -79kJ/mol then the enthalpy change needed for one mole of the substance to freeze is _________.
(a) ΔH = -79kJ/mol
(b) ΔH = +79kJ/mol
(c) ΔH = 0kJ/mol
(d) None of the above