by ohthatpatrick Tue Jul 03, 2018 10:04 pm
Nice prephrase! We know that CFC's damaged the ozone layer because they broke down to chlorine, which is devastating to the ozone layer (it annihilates oxygen atoms).
So we're looking for an answer where we feel like we can assess whether the chemical breaks down to chlorine or whether the chemical otherwise interacts with oxygen atoms in some destructive way.
(D) is saying that we'll figure out whether this chemical would be like chlorine in terms of its ability to mess up oxygen atoms.
(E) is just asking whether UV radiation would break the chemical down. Whether that answer is yes or no doesn't help us know whether the chemical would do damage.
CFC's aren't harmful because they break down. They're harmful because they break down to chlorine, which is harmful to ozone.
If the chemical breaks down into hydrogen and carbon, for example, it's not going to do any damage to the ozone. (he says, not knowing anything about chemistry).
Again, the point is that there's nothing inherently harmful about a chemical breaking down into constituent parts (I think we expect most chemicals to degrade at some point). We're only worried if one of those constituent parts is damaging, and what (E) is asking wouldn't tell us whether or not any of the broken down parts are damaging.
Hope this helps.
(other answers)
(A) We only care about ozone, not other forms of oxygen
(B) We only care about the ozone layer, not some lower layer of the atmosphere
(C) We don't care whether it reacts WITH chlorine; we care whether it reacts LIKE chlorine, by destroying oxygen atoms with total abandon.