Chemistry Questions: Which of the following is a reasonable ground-state electron configuration?

-1s21p62s22p63s2

-1s22s22p63s23p64s24d8

-1s22s22p63p6

-1s22s22p63s1<< My guess

Which of the following is a possible noble gas notation?

-[Xe] 6s26p6

-[Kr] 5s25d85p6

-[Xe] 6s25d106p4

-[Kr] 5s24d105p3

A ground state electron configuration follows the Aufbau Principle that states that electrons should be filled up in orbitals in increasing energy. In the given sequences, the right configuration is

1s2 2s2 2p6 3s2 3p6 4s2 3d8.

2) the possible confirmation that follows Aufbau's principle is

D. - [Kr] 5s24d105p3