Which of the following is a false statement about O2?
a. No pressure can keep it in a liquid state above –118.8° C.
b. Below its boiling point, it remains liquid at ambient pressure.
c. Its critical temperature is above normal room temperature.
d. It cannot be turned into a liquid at room temperature.
ANS: C
Liquid O2 is produced by separating it from a liquefied air mixture at a temperature below its boiling point or critical temperature (–183° C or –297° F). After it is separated from air, the O2 must be maintained as a liquid by being stored in insulated containers below its boiling point. As long as the temperature does not exceed –183° C, the O2 will remain liquid at atmospheric pres-sure. If higher temperatures are needed, higher pressures must be used. If at any time the liquid O2 exceeds its critical temperature of –118.8° C, it will convert immediately to a gas.
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