When is free energy not equal to zero

Question

For which of the following substances is the standard free energy of formation not equal to zero at 298 K?

A. Na(s)

B. O(g)

C. Ne(g)

D. Zn(s)

E. Gd(s)

Answer 1

[Answer: Maussy is correct.

Elements in their standard states (oxygen gas, graphite, metals in their solid states, etc.) have zero standard Gibbs free energy change of formation, as there is no change involved.

Since O is not considered the standard state for oxygen (which should be diatomic oxygen, O2), it is the odd element out here and thus, B is correct answer. ]  

Answer 2

I would say O since the molecule is O2 but not sure