Why is humid air less dense than dry air? a. Molecular movement ...

[panfilo]

Why is humid air less dense than dry air?
  a. Molecular movement of water vapor occupies less space than dry air.
  b. Molecular movement of water vapor occupies more space than dry air.
  c. Water vapor molecules are more compressed than dry air molecules.
  d. Molecules of water vapor have less mass than the displaced nitrogen and oxygen.
  e. Molecules of water vapor have more mass than the displaced nitrogen and oxygen.

Question 2

What is the approximate residence time of water vapor in the lower atmosphere?
 

a. 1 hour
  b. 1 day
  c. 10 days
  d. 100 days
  e. 1000 days

[Sammyo]

Answer to Question 1

d

Answer to Question 2

c

[panfilo]

Thanks for the timely response, appreciate it

[jackie]

Wow, this really help