6which substances have atoms of the same element but different molecular structures?
(1) he(g) and ne(g) (3) k(s) and na(s)
(2) o2(g) and o3(g) (4) p4(s) and s8(s)

Well you want the answer with the same letter in it. A.k.a 2. This means they have the same element in them
O2 (Diatomic oxygen that we breathe) and O3 (Ozone that would be deadly to breathe) have different structures.
So the answer is 2

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