Methane: A) is a permanent gas. B) is a good reflector of ...

[armygirl]

Methane:
 
  A) is a permanent gas.
  B) is a good reflector of thermal radiation.
  C) is removed from the atmosphere by the digestive processes of cattle.
  D) has increased in concentration over the last 50 or so years.

Question 2

Nitrogen:
 
  A) is a variable gas.
  B) has a short residence time.
  C) is a relatively unstable gas.
  D) has little effect on climate.

[katara]

Answer to Question 1

Answer: D

Answer to Question 2

Answer: D