Which of the following represents the lowest vacuum? (A) 10 psia (B) \( 5^{\prime \prime} \mathrm{Hg} \) VAC (C) 5 psig (D) 500 microns

To determine which option represents the lowest vacuum, it’s helpful to understand the concepts of pressure units. The lowest pressure, or highest vacuum, corresponds to the lowest absolute pressure. Among the choices provided, option (D) 500 microns of mercury (Hg) represents a low absolute pressure, as vacuum is often measured in microns. To compare them, you can convert the other units to absolute pressure. Generally, lower values in microns indicate a stronger vacuum! On a fun note, converting from pounds per square inch absolute (psia) to microns can be a bit like solving a puzzle, and each unit tells its own story about how much atmospheric pressure has been removed. Picture a vacuum cleaner sucking up all the air—just like you’d aim for getting into the deepest “clean” space with the least air in those tricky measurements!