Multiple Choice
According to fossil evidence, when did life on Earth first arise?
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24. History of Life on Earth
History of Life on Earth
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Currently scientists think the early atmosphere probably consisted of __________.
A
O2, SO2, and H2O
B
N2, H2O, CO2, NH3, CH4, and O2
C
H2O, CH4, H2, and NH3
D
H2O, CH4, H2, NH3, and O2
E
N2, H2O, CO2, NH3, CH4, and H2
Verified step by step guidance1
Understand the context: The question is about the composition of Earth's early atmosphere, which is a topic in the study of Earth's history and the origin of life.
Recall the scientific consensus: Scientists believe that the early atmosphere was reducing, meaning it had little to no free oxygen (O2). This is important because it helps eliminate options that include O2.
Analyze the options: Look for the presence of O2 in the options, as it is unlikely to be part of the early atmosphere. This helps narrow down the choices.
Consider the chemical components: The early atmosphere is thought to have been composed of simple molecules like nitrogen (N2), water vapor (H2O), carbon dioxide (CO2), ammonia (NH3), methane (CH4), and hydrogen (H2).
Select the correct option: Based on the understanding that the early atmosphere was reducing and composed of these simple molecules, identify the option that includes N2, H2O, CO2, NH3, CH4, and H2 as the correct answer.
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