b. F2 is a molecule but not a compound.
Added 8/7/2012 3:57:22 PM
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He= this is helium, it is an element and is therefore not a molecule or a compound.
F2- is NOT an element it is a MOLECULE. its two Flourides together.
the other choices are compounds since they involve more than one type of element.
Added 8/8/2012 9:02:56 AM
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