Final answer:
The statement is true; manifold pressure is measured in units of inches of mercury (in. Hg). It reflects the pressure in an engine's intake manifold and is measured with a manometer.
Step-by-step explanation:
The statement that manifold pressure is measured in units of inches of mercury is true. Manifold pressure refers to the pressure of the air or fuel/air charge in the intake manifold of an engine. This pressure is an important parameter as it indicates the engine's load and is used to adjust the fuel flow for proper combustion. The pressure is generally measured using a manometer, and for applications like this, it can be expressed in inches of mercury (in. Hg) or millimeters of mercury (mmHg). When using a manometer, particularly an open-end type, the pressure of the gas is equal to the atmospheric pressure plus or minus the difference in the height of mercury between the two arms of the U-tube, depending on whether the pressure is above or below atmospheric pressure.