Question

select the correct answer.
which compound was abundant in precambrian earth’s oceans, before complex life evolved on earth?
a. dissolved oxygen
b. dissolved carbon dioxide
c. dissolved methane
d. dissolved ammonia

Explanation:

In the Precambrian era, before complex life (like oxygen - producing organisms such as plants or algae) evolved, the Earth's atmosphere and oceans had very little oxygen. The early Earth's oceans were rich in dissolved carbon dioxide. Photosynthetic organisms that produce oxygen had not yet evolved in large numbers to change the chemical composition of the oceans and atmosphere. Dissolved methane and ammonia were not as abundant as carbon dioxide in the Precambrian oceans. So the compound that was abundant in Precambrian Earth's oceans before complex life evolved is dissolved carbon dioxide.

Answer:

B. dissolved carbon dioxide