The boiling point is the temperature at which a substance changes from a liquid state to a vapor or gas state.

The boiling point is the temperature at which a substance changes from a liquid state to a vapor or gas state.

• A. True
• B. False
• C. It is the same as melting point
• D. It is the same as freezing point

Answer: (A)

The boiling point is the temperature at which a liquid becomes vapor when its vapor pressure reaches the surrounding pressure. At that moment, bubbles form throughout the liquid, not just at the surface. This is different from melting (solid to liquid) and freezing (liquid to solid). Evaporation can occur at any temperature below the boiling point, but boiling requires the vapor pressure to match the external pressure. For water at sea level, that point is 100°C; changing the surrounding pressure raises or lowers the boiling temperature accordingly.

The boiling point is the temperature at which a liquid becomes vapor when its vapor pressure reaches the surrounding pressure. At that moment, bubbles form throughout the liquid, not just at the surface. This is different from melting (solid to liquid) and freezing (liquid to solid). Evaporation can occur at any temperature below the boiling point, but boiling requires the vapor pressure to match the external pressure. For water at sea level, that point is 100°C; changing the surrounding pressure raises or lowers the boiling temperature accordingly.