Pick out the wrong subshell electronic configuration from those given below?
a) `1s^2 2s^2 2p^7`
b) `1s^2 2s^2 2p^2`
c) `1s^2 2s^2 2p^6 3s^1 `
d)` 1s^2 2s^2 2p^6 3s^2 3p^6 3d^2 4s^1`
e) `1s^2 2s^2 2p^6 3p^6 3d^2 4s^2`

Explanation

a,c,d are wrong