How many of the following electron configurations are allowed?

1s22s22p7 1s22s22p62d1
[Ne]4s24p4
[Ar]3d64s2
1s22s22p83s23p4

Question

How many of the following electron configurations are allowed?

 1s22s22p7 1s22s22p62d1
 [Ne]4s24p4
 [Ar]3d64s2 
1s22s22p83s23p4

alphadxg · Answer

C - is correct, do you want to know why? Too bad I'm gonna tell you why.

alphadxg · Answer

Oops, And when I mean C I mean [Ar] you didn't space out your answers correctly

alphadxg · Answer

1s22s22p7 - no because p7 occupation
1s22s22p62d1 - no 2d oribitals
[Ne]4s24p4 - no 3d fills before 4p
1s22s22p83s23p4 - no 2p8 occupation.

alphadxg · Answer

Medal and fan if your question has been fully answered :)