3. (fus) The latent heats of fusion of pure A and B are , (fus) = 800 K, = 1600 K R R and they may be assumed to be constants. The normal freezing points of A and B are: TA = 400 K, TB 800 K. Species A and B are completely miscible both in the liquid and in the solid phase. The resulting liquid and solid solutions of A and B are ideal solutions at all compositions. A liquid solution of A and B of unknown composition is cooled at constant atmospheric pressure. Experiment indicates that freezing is completed at T = 520 K. Calculate the unknown composition of the liquid solution.