What is the critical temperature of oxygen in Celsius?

• A. -78.5
• B. -118.8
• C. -30
• D. -150

Answer: (B)

The critical temperature of a substance is the highest temperature at which it can exist as a liquid. For oxygen, this temperature is approximately -118.8 degrees Celsius. Above this temperature, oxygen cannot be liquefied, regardless of the pressure applied to it.

At temperatures below -118.8 degrees Celsius, oxygen can exist in both its gaseous and liquid states. This property is significant in various applications, particularly in medical and industrial settings where liquid oxygen is utilized for different processes. Understanding the critical temperature is crucial for safely handling and storing the gas, especially under conditions where it may be pressurized or cooled.

Other temperatures listed do not represent the critical temperature for oxygen, as they fall either below its phase transition point or do not align with established scientific data for this substance. The significance of knowing the critical temperature lies in its implication for the liquefaction processes and handling of gases in the anesthesia machine and other medical equipment.