Which temperature scale has 0 as absolute zero and uses the same increment as Celsius?

• A. Fahrenheit
• B. Celsius
• C. Kelvin
• D. Rankine

Answer: (C)

The crucial idea is that a temperature scale can begin at absolute zero and still use the same size for each degree as the Celsius scale. On this scale, 0 corresponds to the coldest possible state of matter, where molecular motion is essentially zero. The important part is that the unit step is the same as a degree Celsius, so a change of 1 unit represents the same amount of thermal change in both scales. That makes it convenient for scientific work because values shift by a constant offset (0 K is -273.15 °C) but step sizes match, so calculations of differences are straightforward. This combination—absolute zero at zero and 1 unit equal to 1 Celsius degree—identifies the Kelvin scale. Other scales place zero at different physical points or use different degree sizes, so they don’t meet both conditions simultaneously.