Which of the following breaks down the ozone layer when combined with cold and light?

carbon dioxide

methane

oxygen

cholofluorocarbons (cfcs)

Use the drop-down menu to match the following definitions to the corresponding terms. the total variety of organisms that live in the biosphere a group of organisms that breed and produce offspring that can breed all of the biotic and abiotic factors in an area

Up to what percentage of the world's flora consisted of cycads during the triassic period? 100% 75% 50% 20%

The big bang theory suggest that the universe is about - 300 million years old - 4.6 billion years old - 30 billion years old - 13 billion years old