Question

what are the two most common greenhouse gases in the atmosphere?
a. water vapor ($h_2o$) and carbon dioxide ($co_2$)
b. nitrogen (n) and oxygen ($o_2$)
c. carbon dioxide ($co_2$) and oxygen ($o_2$)
d. methane ($ch_4$) and helium (he)

Explanation:

Water vapor is the most abundant greenhouse gas in Earth's atmosphere, and carbon dioxide is the second most common human-influenced and naturally occurring greenhouse gas. Nitrogen and oxygen make up most of the atmosphere but are not greenhouse gases. Helium is not a greenhouse gas, and oxygen does not act as one either.

Answer:

A. Water vapor ($H_2O$) and Carbon Dioxide ($CO_2$)