A substance will sublime rather than melt if ______

Question

its critical point occurs at a temp above room temp

its triple point occurs at a pressure below atmospheric pressure

its triple point occurs at a pressure above atmospheric pressure

its critical point occurs at a pressure above atmospheric pressure

its critical temp is above its normal boiling point

(under normal conditions)

Answer 1

Carbon dioxide (CO2) is a good example of this.

This is the phase diagram for it:

http://www.chemicalogic.com/images/phase...

As we can see, the triple point occurs at a pressure below atmosphere pressure (1 atm).  Thus, that would be your answer.

[Answer: see above]