Answer:
During respiration in plants and animals, carbon dioxide is returned to the environment.
Step-by-step explanation:
Carbon dioxide is a dull gas with a thickness of about 60% which is higher than that of dry air. Carbon dioxide comprises of a carbon particle covalently twofold attached to two oxygen molecules. It is seen in atmosphere in traces.
When organism such as plant, animals, algae and other microorganism respires, it leads to return of carbon dioxide to the environment as it is the major compound formed due to the metabolic activity in them. Apart from this burning of fossil fuels and deforestation also act as cause of returning of carbon dioxide to the environment.