The increase in internal energy of 1 kg of water at 100° C when it is converted into steam at the same temperature and 1 atm $\left(100\mathrm{kPa}\right)$ will be : [The density of water and steam are $1000\mathrm{kg}/{\mathrm{m}}^3$ and $0.6\mathrm{kg}/{\mathrm{m}}^3$ respectively. The latent heat of vaporization of water is $2.25\times {10}^6\mathrm{J}/\mathrm{kg}$.]