Answer
Solid $\rightarrow$ gas
Work Step by Step
At $-80^{\circ}C$, $CO_{2}$ is a solid. As pressure reduces, it starts to transition towards the gaseous state. This can be observed from $Fig. 11.39(b)$.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.