An aluminium vessel of mass 0.5 kg contains 0.2 kg of water at 20∘C. A block of iron of mass 0.2 kg at 100∘C is gently put into the water. Find the equilibrium temperature of the mixture. Specific heat capacities of aluminium, iron and water are 910 Kg−1K−1470 J kg−1K−1 and 4200 J kg−1K−1 respectively.