Question

the correct sequence of filling the subshell is??

Answer 1

1s 2s 2p 3s 3p 4s 3d 4p 5s 4d and so on

Answer 2

The correct sequence of filling the subshell is 
1s< 2s <2p <3s< 3p< 4s <3d <4p< 5s< 4d<5p,6s and it continues