Since you know ion's electrical charge (as two) and ammonia's electrical charge (as zero), you retrieve that this complex belongs to bi-valent zinc compounds.
You return to a suggestions which a great scientist (e.g. SOM) sent us : transition's metals lose "s electrons" before "d electrons". "S electrons" are two, no more, so zinc atoms maintain all its "d electrons".
As any bi-valent zinc compounds, [Zn(NH3)4]++ results "3d10".
Answers & Comments
Verified answer
Lancenigo di Villorba (TV), Italy
Your complex is tetra-amino-zinc(II) ion.
Since you know ion's electrical charge (as two) and ammonia's electrical charge (as zero), you retrieve that this complex belongs to bi-valent zinc compounds.
You return to a suggestions which a great scientist (e.g. SOM) sent us : transition's metals lose "s electrons" before "d electrons". "S electrons" are two, no more, so zinc atoms maintain all its "d electrons".
As any bi-valent zinc compounds, [Zn(NH3)4]++ results "3d10".
I hope this helps you.