Venus and Earth probably formed with similar amounts of carbon dioxide in their secondary atmospheres. Which of the following is TRUE?
A) The majority of Earth's carbon dioxide escaped into space because of its hotter temperature, while Venus's carbon dioxide remains gravitationally bound to Venus.
B) The majority of Earth's carbon is now bound up in rock while Venus's remains in its atmosphere.
C) Earth lost more of its secondary atmosphere because it was bombarded by more planetesimals than Venus.
D) The majority of Earth's carbon was absorbed by plants during photosynthesis.
E) Earth and Venus still have equal amounts of carbon dioxide in their atmospheres.

Question

Quizplus · Accepted Answer

Studies show that Venus and Earth probably formed with similar amounts of carbon dioxide in their secondary atmospheres. However, Venus experienced a runaway greenhouse effect that caused its atmosphere to become extremely dense in carbon dioxide. As a result, the majority of Venus's carbon is still bound up in its atmosphere. In contrast, Earth's carbon was mostly absorbed by rock during the planet's early history, so the majority of Earth's carbon is now bound up in rock.

Venus and Earth Probably Formed with Similar Amounts of Carbon