Final answer:
Carbon dioxide gas is present in Earth's atmosphere due to photosynthesis.
Explanation:
Carbon dioxide gas exists entirely as a result of photosynthesis in Earth's atmosphere. During photosynthesis, plants take in carbon dioxide from the air and convert it into glucose, releasing oxygen as a byproduct.
Learn more about photosynthesis in Earth's atmosphere here:
https://brainly.com/question/153854
