Unlike CO2 or N2O, O2 cannot be stored as a liquid at room temperature but must be kept in spe-cial cryogenic containers. Why is this so?

a. O2 is 20 times less diffusible than CO2, N2O, or cyclopropane.
b. O2 has a critical temperature well below room temperature.
c. O2 has an extremely high gas solubility coefficient.
d. O2 has a boiling point below well below room temperature.

ANS: B
Oxygen has a critical temperature well below room temperature (–181.4° F [–118.6° C]). Liquid O2 must continually be stored below this temperature, or it reverts to its gaseous state.