The most abundant greenhouse gas in the earth's atmosphere is: ...

[tsand2]

The most abundant greenhouse gas in the earth's atmosphere is:
  a. carbon dioxide (CO2).
  b. nitrous oxide (N2O).
  c. water vapor (H2O).
  d. methane (CH4).
  e. chlorofluorocarbons (CFCs).

Question 2

The only substance near the earth's surface that is found naturally in the atmosphere as a solid,
  liquid, and a gas is:
  a. carbon dioxide.
  b. water.
  c. molecular oxygen.
  d. ozone.
  e. carbon.

[okolip]

Answer to Question 1

c

Answer to Question 2

b

[tsand2]

Great answer, keep it coming

[olderstudent]

Thanks for the timely response, appreciate it