`3 d^(10) 4 s^(0)` electronic configuration exhibits

State true or false : 3d^0 4s^0 electronic configuration exhibits by Ti^(+4)

[Ar]^(18) 3d^(10) 4s^(1) electronic configuration belongs to

[Ar]^(18) 3d^(10) 4s^(1) electronic configuration belongs to

Explain why (i) the three electrons present in 2p subshell nitrogen remain unpaired. (ii) in potassium, the 19th electron enters into 4s subshell instead of 3d subshell, (iii) chromium has configuration 3d^(5) 4s^(1) instead of 3d^(4), 4s^2, (iv) the electronic configuration of zinc can be represented as [Ar] 3d^(10) 4s^(2)?

The electronic configuration of valence shell of Cu is 3d^(10)4s^(2) . How is this configuration explained ?