What is the physical state of water at: (a) 25°C (b) 0°C (c) 100°C

(a) The physical state of water at 25°C is liquid. This is because the temperature is the normal room temperature condition in which water remains in its liquid state.
(b) The freezing point of water is 0°C. The physical state of water at 0°C changes from liquid state to solid state and at the end of the process water is present as ice, which is the solid state.
(c) The boiling point of water is 100°C. The physical state of water at 100°C changes where water is converted to steam. At the end of boiling, the water is completely converted to steam which is the gaseous state of water.