CFCs are safe on Earth's surface but become very destructive to ozone when exposed to UV light in the upper ? Upper what

CFCs are broken down by UV photolysis, but the process takes a long time since it takes decades to cycle all of the air in the troposphere through the upper stratosphere. ... The photolysis of CFCs generates a highly reactive chlorine atom that can attack ozone or form compounds that destroy ozone. upper stratosphere should be your answer

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)

many phylogenetic trees have a single lineage at the base representing a common ancestor. a lineage that evolved early from the root and remains unbranched is called basal taxon. when two lineages stem from the same branch point, they are called sister taxa.

can i get the brainliest pls

explanation: