Which statement correctly describes boiling?

Which statement correctly describes boiling?

• A. Boiling occurs when a liquid's vapor pressure equals the external pressure.
• B. Boiling occurs when a liquid freezes.
• C. Boiling occurs when external pressure exceeds vapor pressure.
• D. Boiling occurs at all temperatures regardless of vapor pressure.

Answer: (D)

Boiling happens when the liquid’s vapor pressure reaches the pressure exerted on it from the surroundings. When these two pressures meet, bubbles of vapor form throughout the liquid and rise to the surface. This is why there is a specific boiling point for a given pressure—the temperature at which the vapor pressure equals the external pressure. If the surrounding pressure is higher than the liquid’s vapor pressure at a particular temperature, the liquid won’t boil until you heat it more to raise its vapor pressure to that higher external pressure. If the surrounding pressure is lower, boiling can occur at a lower temperature. This is also why water boils at a lower temperature at high altitudes and at a higher temperature under pressure. The idea that boiling occurs at all temperatures regardless of vapor pressure isn’t correct, because boiling requires the vapor pressure to match (or effectively overcome) the surrounding pressure. It’s not about freezing or about boiling under any condition of pressure without that balance.

Boiling happens when the liquid’s vapor pressure reaches the pressure exerted on it from the surroundings. When these two pressures meet, bubbles of vapor form throughout the liquid and rise to the surface. This is why there is a specific boiling point for a given pressure—the temperature at which the vapor pressure equals the external pressure.

If the surrounding pressure is higher than the liquid’s vapor pressure at a particular temperature, the liquid won’t boil until you heat it more to raise its vapor pressure to that higher external pressure. If the surrounding pressure is lower, boiling can occur at a lower temperature. This is also why water boils at a lower temperature at high altitudes and at a higher temperature under pressure.

The idea that boiling occurs at all temperatures regardless of vapor pressure isn’t correct, because boiling requires the vapor pressure to match (or effectively overcome) the surrounding pressure. It’s not about freezing or about boiling under any condition of pressure without that balance.