What is the boiling point of water at standard conditions?

• A. 100°C
• B. 0°C
• C. 212°F
• D. 50°C

Answer: (A)

The boiling point at standard conditions is the temperature at which liquid water turns into vapor when the surrounding pressure is 1 atmosphere (about 101.3 kPa). At that pressure, water boils at 100°C, which is the direct Celsius value you’d use in science. The same temperature is 212°F, which explains why that option is also correct in Fahrenheit terms, but the standard scientific convention uses Celsius, so 100°C is the best choice. The other temperatures aren’t boiling points at 1 atm: 0°C is the freezing point, and 50°C is well below the boiling point.