Question

Neon is an inert gas and has the atomic number of 10. Which of the following correctly depicts its electron configuration? 1s22d8 1s22s43p4 1s22s22p6 1s22s23p44d2

Answer 1

I think the answer is 1s²2s²2p⁶.  Since neon has an atomic number of 10, we know that it needs to have 10 electrons and since it is in the second row it cannot have any d electrons which makes the first option incorrect.  The second option is incorrect because the 2s⁴ can't exist since s orbitals can only hold 2 electrons.  The fourth option cannot be right because it again neon cannot have d electrons due to it being in the second row.

I hope this helps.  Let me know if anything is unclear.