Mold Remediation Certification Practice Exam

What does dry ice give off when it sublimates?

1. Oxygen

2. Carbon dioxide

3. Water vapor

4. Nitrogen

The correct answer is: Carbon dioxide

When dry ice sublimates, it undergoes a phase change from solid to gas without passing through a liquid state. This process releases carbon dioxide gas (CO2) into the atmosphere. Dry ice is actually solidified carbon dioxide, and as it warms, it transforms directly into CO2 gas due to the heat from the surrounding environment. This is why the correct answer is carbon dioxide. The other substances listed, such as oxygen, water vapor, and nitrogen, do not occur during the sublimation of dry ice. For instance, while water vapor is produced when ice (H2O) melts, that is a different process entirely, and dry ice specifically does not release water during its sublimation. Similarly, nitrogen is a separate gas found in the atmosphere and is not associated with the sublimation of carbon dioxide. Therefore, understanding that dry ice is primarily composed of carbon dioxide is fundamental to recognizing why carbon dioxide is the correct answer.