The molality of a urea solution in which 0.0200 g of urea (NH2CONH2) is added to 0.400 dm3 of water at STP is

1 dm3=1000 cm3=1L=1 kg0.400 dm3 of H2O at STP = 0.400 kg of H2O (density = 1.0 g /cm)Moles of urea =0.020060∴ Molality=Moles of solute (urea)kg of solvent=0.020/600.400=8.33×10−4 mol kg−1