77 K at one atmosphere is equivalent to what Celsius temperature?

• A. -77 C
• B. 23 C
• C. -196 C
• D. 0 C

Answer: (C)

When converting from Kelvin to Celsius, subtract 273.15: T(C) = T(K) − 273.15.

For 77 K: 77 − 273.15 = -196.15 °C, which rounds to about -196 °C. So the Celsius temperature equivalent is -196 C.

The other options don’t fit because they correspond to Celsius values that convert to Kelvin values far from 77 K (for example, -77 °C would be about 196 K; 23 °C would be about 296 K; 0 °C would be 273.15 K).