What is the boiling point of water at standard pressure?

• A. 80 Celsius, 176 Fahrenheit, 353 Kelvin
• B. 0 Celsius, 32 Fahrenheit, 273 Kelvin
• C. 120 Celsius, 248 Fahrenheit, 393 Kelvin
• D. 100 Celsius, 212 Fahrenheit, 373 Kelvin

Answer: (D)

Boiling point is the temperature at which a liquid’s vapor pressure equals the surrounding pressure. At standard pressure, defined as 1 atmosphere (about 101.3 kPa), water boils at 100°C, which is 212°F and 373 K. This is the reference boiling point for sea level conditions. The other temperatures reflect water boiling under different pressures: 0°C is the freezing point, not boiling at standard pressure; 80°C would boil at a lower external pressure than 1 atm; 120°C would require a higher external pressure because increasing pressure raises the boiling point. So the exact boiling point at standard pressure is 100°C / 212°F / 373 K.