2 kg of ice at−20oC is mixed with 5 kg of water at 20oC in an insulating vessel having a negligible heat capacity. Calculate the final mass of water remaining in the container. lt is given that the specific heats of water and ice are 1 kca1/kg/∘C and 0.5 kca1/kg/∘C respectively while the latent heat of fusion of ice is 80 kcal/kg :