On which temperature scale does the boiling point of water equal 100 degrees?

The boiling point of water is defined as 100 degrees on the Celsius scale. Celsius is based on the properties of water, highlighting its critical points: 0 degrees is the freezing point, and 100 degrees is the boiling point at standard atmospheric pressure. This scale is widely used across the world in scientific contexts and everyday applications, particularly in most parts of the world outside the United States.

Understanding the Celsius scale is essential for instrumentation and temperature measurement as it provides a straightforward and intuitive way to discuss thermal phenomena relevant to both science and industry. In comparison, the other temperature scales have different fixed points for water. For example, using the Fahrenheit scale, water boils at 212 degrees, and the Kelvin scale measures absolute temperatures starting from absolute zero, placing the boiling point of water at 373.15 Kelvin. Meanwhile, the Rankine scale, which is another absolute scale used primarily in thermodynamics, sets the boiling point of water at 671.67 Rankine. Thus, the Celsius scale clearly defines water's boiling point at 100 degrees, making it the appropriate answer.