Answer: The pressure 12.2 psi is expressed in millimeters of mercury (mm Hg) as 630.9221 mm Hg.
Step-by-step explanation:
Given: Pressure = 12.2 psi
According to the standard conversion of units, 14.7 psi = 1 atm = 760mmHg.
Therefore, 1 psi equal to how many mm Hg is calculated as follows.

Hence, 12.2 psi will be converted into mm Hg as follows.

Thus, we can conclude that the pressure 12.2 psi is expressed in millimeters of mercury (mm Hg) as 630.9221 mm Hg.