Question

as we know that carbon burns and oxygen supports burning . and we also know that carbon dioxide is a mixture of carbon and oxygen then why carbon dioxide don t burn

Answer 1

Carbon burns and oxygen supports burning is a true statement. But carbon dioxide is not a mixture of carbon and oxygen, it is actually a naturally occuring chemical compound which composed of 2 oxygen atoms bonded with carbon atom, give rising to totally different chemical and physical properties in comparison to its constituents. And CO₂ do not support burning instead it is used for extinguishing fires.