Which statement defines the boiling point most accurately?

Which statement defines the boiling point most accurately?

• A. The temperature at which a liquid becomes a solid.
• B. The temperature at which a liquid becomes a gas.
• C. The temperature at which a solid becomes a liquid.
• D. The temperature at which a gas becomes a liquid.

Answer: (B)

At its essence, the boiling point is the temperature at which a liquid changes into a gas, occurring when the liquid’s vapor pressure equals the surrounding pressure. At that temperature, bubbles of vapor form within the liquid and rise to the surface, signaling a liquid-to-gas transition. This value depends on pressure; for water at sea level, it’s 100°C. The other phase changes describe different transitions: solid to liquid is melting, liquid to solid is freezing, and gas to liquid is condensation. So the description of a liquid becoming a gas at a specific temperature best captures what the boiling point means.

At its essence, the boiling point is the temperature at which a liquid changes into a gas, occurring when the liquid’s vapor pressure equals the surrounding pressure. At that temperature, bubbles of vapor form within the liquid and rise to the surface, signaling a liquid-to-gas transition. This value depends on pressure; for water at sea level, it’s 100°C. The other phase changes describe different transitions: solid to liquid is melting, liquid to solid is freezing, and gas to liquid is condensation. So the description of a liquid becoming a gas at a specific temperature best captures what the boiling point means.