Ice is solid at 0°C i.e., 273° K. The molecules of ice are tightly packed. These molecules have to overcome the force of attraction with which they are held and hence they gain this heat from the surrounding but the temperature remains the same as their energy is used to overcome the force of attraction between the particles. The particles have their state and starts vibrating freely and a stage reaches when the solid ice melts and is converted to liquid state at the same temperature i.e., 273 K.