Question

When the pressure–temperature graph of different gases is extrapolated (extended backwards), all lines meet the temperature axis at one common point. What does this point represent?

Options

• The triple point of water

• The boiling point of a specific gas

• The lowest theoretically possible temperature (−273.15 °C)

• The temperature at which gases liquefy

Answer 1

The lowest theoretically possible temperature (−273.15 °C)

Explanation:

Extrapolating P–T graphs backwards for any gas shows that pressure would reach zero at −273.15 °C. This universal convergence point, independent of the gas used, defines absolute zero.