Answer to Question 1
ANS: A
When a gas is not fully saturated, its water vapor content can be expressed in relative terms using a measure called relative humidity.
Answer to Question 2
ANS: A
For example, air that is fully saturated with water vapor at 37 C and 760 mm Hg has a water vapor pressure of 47 mm Hg and an absolute humidity of 43.8 mg/L.