A scientist wants to perform an experiment in aqueous solution in a hill station where the boiling point of water is 98.98°C. How much urea $(mol.wt \,60 g\, mol^{-1})$ is to be added by him to 2 kg of water to get the boiling point 100°C at the same place? ($K_b$ of water=0.51$K kg mol^{-1}$)