How many grams of ice at 0°C can be melted by the addition of 500 J of heat? (The molar heat of fusion for ice is 6.02 kJ mol^-1)

As 6020 J is required to melt 18 g of ice at 0°C 
So, 1 J would melt $=\frac{18}{6020}\mathrm{g}\text{ of iceat }{0}^{\circ }\mathrm{C}\approx 3\times {10}^{-3}\mathrm{g}$
Hence 500 J would melt = 500 x 3 x 10^-3 g of ice at 0°C = 1.5 g