Which gases are not considered compressed until a certain pressure is reached?

The chosen answer accurately reflects the characteristics of gases and their classification regarding compression. Gases without any health or physical hazard properties are generally considered non-hazardous under normal conditions and might not be compressed until a specific pressure threshold is reached. This is particularly relevant in medical settings where the management of gases is critical for patient safety.

In contrast, all gases do become compressed at various pressures, but the distinction highlights that certain gases, especially those that are safer and lack hazard properties, can remain in a gaseous state until significant pressure is applied. This distinguishes them from hazardous gases or other types that would have different handling requirements.

Other options do not accurately capture the intent of the question. For instance, all gases under normal conditions may experience compression, but this does not specifically relate to their health or hazard properties. Similarly, only high-pressure gases and gases that are completely liquid do not embrace the broader context of non-hazardous gases remaining in a gaseous state until a certain pressure is reached.