Thermometry basics – which temperature scale assigns 0° to the ice point and 80° to the steam point at standard pressure?

Introduction / Context:
Multiple historical temperature scales exist in thermal engineering. While SI practice relies on kelvin and Celsius, older or regional literature sometimes references the Réaumur (Reaumur) and Fahrenheit scales. Recognising their fixed points prevents misinterpretation of legacy data, calibration plates, or examination items.

Given Data / Assumptions:

• “Ice point” means the equilibrium temperature of pure ice and water at 1 atm.
• “Steam point” means the equilibrium temperature of saturated water and steam at 1 atm.
• We seek the scale that assigns 0° at the ice point and 80° at the steam point.

Concept / Approach:
By definition, the Reaumur scale sets 0°R (Re) at the ice point and 80°R (Re) at the steam point, creating an 80-division interval. The Celsius scale assigns 0 °C and 100 °C to the same points. Fahrenheit assigns 32 °F and 212 °F. Rankine is an absolute scale with degree size equal to Fahrenheit degrees and zero at absolute zero, not at the ice point.

Step-by-Step Solution:

Verification / Alternative check:
Conversion formulas: C = (5/4) Re; hence Re = (4/5) C, consistent with 100 °C → 80 °Re.

Why Other Options Are Wrong:

• Celsius: Steam point is 100 °C, not 80.
• Fahrenheit: Fixed points 32 and 212.
• Rankine: Absolute scale; does not place 0 at the ice point.

Common Pitfalls:
Spelling confusions (Celcius/Farenhite/Reumur) and mixing up absolute vs relative scales.

Final Answer:
Reaumur