Which of the following species are isoelectronic with each other?

Question

cometailcane · Answer

C, Cl-, Mn2+, B-, Ar, Zn, Fe3+, Ge2+

lυἶცἶ0210 · Answer

Isometric means they would have the same number of valence electrons and/or configuration. 

Any guesses?

cometailcane · Answer

No clue. I missed the class where we learned this

lυἶცἶ0210 · Answer

Okay, I'll give you an example from your choices that you have. 

Carbon (C) as a neutral atom has 6 valence electrons, and the config of $1s^2~2s^2~2p^2 $ right? 
Boron (B) as a neutral atom has only 5 valence electrons, and the config of ((1s^2~2s^2~2p^1 \).
But since this this $\Large B^{\color{red}{-}} $, meaning it has an extra electron, it becomes $1s^2~2s^2~2p^2 $. Having the same config as carbon, therefore they C and $B^- $ are isoelectronic.

lυἶცἶ0210 · Answer

Take the chlorine ion ( $Cl^- $) and try to find it's isoelectronic counterpart. One that also has 8 valence electrons.

cometailcane · Answer

Okay so these are the other pairing I came up with: Ar & Cl
Zn & Ge2+
Mn2+ & Fe3+

cometailcane · Answer

What about for Be2+, F-, Fe2+, N3-, He, S2-, Co3+, Ar? I'm having trouble with some of them

cometailcane · Answer

These are the two that I got but I'm not sure they're right. Ar & F-
Be2 & He

lυἶცἶ0210 · Answer

Be 2+ and He would be (:

Ar and F- wouldn't be thoo

cometailcane · Answer

Ar and S2-?