Which ion does not have a noble gas configuration in its ground state? which ion does not have a noble gas configuration in its ground state? al3+ sc3+ as3- ga3+?

The correct answer is Ga3+.  

Electron configuration of Al is [Ne] 3s2 3p1  

Electron configuration of Al3+ is [Ne]  

So the electron configuration of Al3+ is like that of Ne.  

Electron configuration of Sc is [Ar] 3d1 4s2  

Electron configuration of Sc3+ is [Ar]  

So the electron configuration of Sc3+ is like that of Ar.  

Electron configuration of As is [Ar] 3d10 4s2 4p3  

Electron configuration of As3- is [Ar] 3d10 4s2 4p6

So the electron configuration of As3- is like that of Kr

Electron configuration of Kr [Ar] 3d10 4s2 4p6  

Electron configuration of Ga is [Ar] 3d10 4s2 4p1

Electron configuration of Ga3+ is [Ar]3d10

The presence of the ten d orbital electrons prevents Ga3+ from having the same electron configuration as Argon.  

All other choices have the same electron configurations as a noble gas.  

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