[Sis290025]

Which of the following three sets consist of atoms or ions with the same electron configuration in the ground state?

I. O (2-), Ne, and Mg (2+)
II. Ni, Cu+, Zn 2+
III. Hg, Tl+, and Pb (2+)

a. all but (II)
b. all but (I)
c. all three sets
d. only (I)

For this, I am not sure of the question's wording. Must all three ions/atoms of each Roman numeral have the same electron configuration in the ground state or must at least one of each Roman numeral have the same electronic configuration? If it is the latter, wouldn't the correct choice be all three sets?

Thank you for any replies.

[Albert]

In my opinion (but I'm not sure ), the answer is a. all but II.

In fact, Cu has the following configuration:
Cu: [Ar], 4s1, 3d10.

So, the stablest configuration for Cu+ should be:
Cu+: [Ar], 4s0, 3d10.

There is another post, somewhere in this website, that deals with this topic.

[Sis290025]

So a change in the number of electrons is not really a different electron configuration; what matters is if there is an addition or subtraction of a subshell?