By using heat of fusion (6.02 kJ / mol) of water as a conversion factor to determine the moles of water then use molar mass (18.02 g/mol) of water as a conversion factor to determine the mass of water and finally use the mass of one ice cube as a conversion factor to determine the number of ice cubes that absorbs 67.1 kJ energy:
67.1 kJ * [tex] \frac{1 mole H2O}{6.02 kJ} * \frac{18.02 g H2O}{1 mol H2O} * \frac{1 ice cube}{20.0 g H2O} = 10 ice cubes [/tex]
So the correct answer is 10 ice cubes
