Which of the following will not be removed from air by a filter?

Water vapor is a gas that remains in the air and is not typically removed by standard filters. Unlike liquid contaminants or droplets, which can be physically trapped by filters, water vapor exists in a gaseous state and requires different methods for removal, such as refrigeration or desiccant drying.

Contaminants, compressor oil, and condensed water are all physical substances that can be effectively captured by various types of air filters. These filters can capture larger particulates or droplets, but water vapor, due to its gaseous nature, passes through without being collected. Understanding the physical states of substances helps clarify why certain items are removed by filters while others, such as water vapor, are not.