Earth's first atmosphere (approximately 4.6 billion years ago) was most likely composed of ____.
A) nitrogen and oxygen
B) hydrogen and helium
C) carbon dioxide and nitrogen
D) oxygen and carbon dioxide
Question 2
A chart that plots how air temperature has changed over the past five days at a given station is a(n) ____.
A) sounding
B) meteogram
C) atmospheric model
D) ensemble forecast
