Chemistry

Question Analysis
This question involves applying triple point knowledge to predict the phase change of CO₂ at standard atmospheric pressure.
The main focus is on understanding that below the triple point pressure, the liquid phase of a substance is not stable.

Key Concept Explanation
The triple point pressure is the minimum pressure required for the liquid phase to exist.
For CO₂, standard atmospheric pressure (1 bar) is below its triple point pressure (5.18 bar).
Therefore, liquid CO₂ cannot form at 1 bar, regardless of temperature. Heating solid CO₂ at 1 bar will cause it to sublime directly to gas.

Step-by-Step Solution
1. Compare standard atmospheric pressure (1 bar) to CO₂’s triple point pressure (5.18 bar): 1 bar < 5.18 bar.
2. Recall the rule for pressure below triple point: No stable liquid phase.
3. Analyze the phase change of solid CO₂ when heated at 1 bar...