Question

Which best describes the atmosphere of the early Earth?

A.
Little or no oxygen, mostly carbon dioxide, water vapor, and nitrogen
B.
Little or no carbon dioxide, mostly oxygen, water vapor, and nitrogen
C.
Little or no water vapor, mostly oxygen and carbon dioxide, with some nitrogen
Large amounts of hydrogen cyanide with low amounts of carbon dioxide and oxygen
D.

Answer 1

Astronomical and geological evidence suggests that active volcanoes covered early Earth. In addition, with no protective atmosphere, Earth was probably very hot and constantly bombarded with comets and asteroids. Around 4.2 billion years ago, Earth cooled enough for the surface to solidify and for water vapor to condense and fall as rain. This allowed permanent oceans to form.