491 K is equivalent to

Analyze the question: You are asked to convert a temperature from kelvin (K) to degrees Celsius (°C).

Concept: The Kelvin and Celsius scales are related by:

T(K) = θ(°C) + 273

So, θ(°C) = T(K) − 273

Solution:

θ = 491 − 273 = 218 °C

Check against the options:

• A. 273 °C: no
• B. 218 °C: matches
• C. 373 °C: no
• D. 491 °C: no
• E. 764 °C: this comes from wrongly adding 273 to 491

Tip: To go from Celsius to Kelvin, add 273. To go from Kelvin to Celsius, subtract 273. A quick check is that Kelvin values are always larger than the Celsius values for the same temperature, so 491 K must give a smaller number in °C. That immediately rules out options D and E.