Question

write electronic configuration of Cu(2g).​

Answer 1

Electronic configuration of Cu is 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d9 ([Ar] 4s2, 3d9), whereas for Cu2+ is [Ar], 3d9. I found some periodic tables and electronic configuration notes, there is [Ar] 4s1, 3d10 for Cu.