At a temperature of 150 °C and standard atmospheric pressure, what is the phase of water?

• A. Gas (steam)
• B. Solid (ice)
• C. Liquid
• D. Plasma

Answer: (A)

Verified step by step guidance

1. Identify the given conditions: temperature = 150 °C and pressure = 1 atm (standard atmospheric pressure).
2. Recall the phase diagram of water, which shows the state of water (solid, liquid, gas) at different temperatures and pressures.
3. Note the normal boiling point of water at 1 atm is 100 °C, and the melting point is 0 °C.
4. Since 150 °C is above 100 °C at 1 atm, water will be in the gaseous phase (steam).
5. Conclude that under these conditions, water exists as a gas (steam).