1. Is atmospheric pressure always equal to 1 atm?
2. What is absolute pressure? Gauge pressure?
3. The gauge pressure of a gas is -20 mm Hg at a point where atmospheric pressure is 755 mm Hg. How else can be gas pressure be expressed in term of mm Hg? (Give two values.)
4. A mercury column is open to the atmosphere on as day when atmospheric pressure is 29.9 in Hg. What is the gauge pressure 4 in. below the surface? The absolute pressure? (Give the answers in in. Hg.)