(a). 250°C: At this temperature, water will be in a gaseous state.
The boiling point of water, which is the temperature at which it changes from liquid to gas, is 100°C. Since 250°C is significantly higher than the boiling point, all the water will have converted into steam (water vapor).
(b). 100°C: At 100°C, water is at its boiling point. This means it exists in a mixture of both liquid and gas.
Some water molecules will be energetic enough to escape the liquid and become steam, while others remain in the liquid state. This is why you see bubbles forming and rising during boiling. As you continue to add heat, all the water will eventually convert to steam.