When a given mass of liquid water boils and converts into steam at 373 K and 1 atm pressure :

Step-by-step solution

During the boiling process, water converts into steam, which leads to a massive increase in volume ( V > 0 ). Because the volume increases, positive work is done by the water-steam system on the atmosphere ( W > 0 ). The system absorbs heat in the form of latent heat of vaporization ( Q > 0 ). According to the first law of thermodynamics, Q = U + W . Since the heat absorbed is significantly larger than the work done, the change in internal energy U is positive. Thus, the internal energy of the system increases. Ans