On dissolving 0.5 g of a non-volatile non-ionic solute to 39 g of benzene, its vapor pressure decreases from 650 m m H g to 640 m m H g . The depression of freezing point of benzene (in K ) upon addition of the solute is _______ (Given data: Molar mass and the molal freezing point depression constant of benzene are 78 g m o l - 1 and 5.12 K k g m o l - 1 , respectively)