(a) Water will be in gaseous state at 250°C. The boiling point of water is 100°C. Heating the water above this temperature will change it into gaseous state.

(b) The boiling point of water is 100°C. At this temperature the liquid starts changing into gas. Boiling is a bulk phenomenon. Particles from the bulk of the liquid gain enough energy to change into the vapour state. Hence, the physical state of water at 100°C will be both ‘liquid’ and ‘gaseous’ state.