In a phase diagram, at which temperature does a substance vaporize under standard atmospheric pressure?

• A. At its melting point
• B. At its triple point
• C. At its boiling point
• D. At its critical temperature

Answer: (C)

Verified step by step guidance

1. Understand that a phase diagram shows the states of matter (solid, liquid, gas) of a substance at different temperatures and pressures.
2. Recognize that vaporization is the process where a liquid turns into a gas.
3. Identify that standard atmospheric pressure is 1 atm, which is a common reference pressure in phase diagrams.
4. Recall that the boiling point is defined as the temperature at which a liquid's vapor pressure equals the external pressure (here, 1 atm), causing it to vaporize.
5. Therefore, on a phase diagram, the temperature at which a substance vaporizes under standard atmospheric pressure corresponds to its boiling point.