Electron Config: Same for O, Ne, Mg (2+); Ni, Zn (2+); Hg, Tl+, Pb (2+)

[Soaring Crane]

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)
Is it all but ii. because Cu loses its 4s shell?
Thanks.

 

[Cesium]

atoms or ions with the same electron configuration in the ground state?

Aka isoelectronic series

Well O2-, Ne, and Mg2+ all have the configuration of [Ne]

and for 2 Ni is [Ar] 3d8 4s2
and Zn is [Ar] 3d10 4s2
Zn+2 would then be [Ar] 3d10 because you take from the outermost shell
Cu is [Ar] 3d10 4s1 so Cu+ would be [Ar] 3d10

So 2 isn't isoelectronic

For #3, Hg is [Xe] 4f14 5d10 6s2
Tl is [Xe] 4f14 5d10 6s2 6p1 so Tl+ is indeed [Xe] 4f14 5d10 6s2
Pb is [Xe] 4f14 5d10 6s2 6p2 so Pb+2 is indeed [Xe] 4f14 5d10 6s2

So you are indeed correct but your explanation doesn't quite make sense to me.