Which greenhouse gas has maximum average residence time in the atmosphere?

Chlorofluorocarbons (CFCs) have the longest atmospheric residence time among the listed greenhouse gases, ranging from about 45 years (CFC-11) to over 100 years (CFC-12), with some species persisting for several hundred years. Methane has an atmospheric lifetime of roughly 12 years, nitrous oxide about 114 years (still shorter than many CFCs), while water vapour has a very short residence time of only about 9-10 days. Hence CFCs have the maximum average residence time.