So, what units do we use to express pressure? A few. There are torr, millimeters
of mercury (mmHg), and atmospheres (atm): 1 torr and 1 mmHg are equal, and
760 torr (or 760 mmHg) = 1 atm.
What instruments are used to measure pressure? The barometer and the
manometer. Both the barometer and manometer involve the use of the liquid
metal mercury (Hg) to determine atmospheric pressure.
Pressure Basics
Units of pressure: standard pressure = 760 torr = 760 mmHg = 1 atm
Pressure is measured with a barometer or a manometer
Any question on the exam that contains any of the above terms will in some
way be concerned with pressure. So when you see such a question, think
pressure and you’ll be on the right track.