Question

Which set of orbitals is listed in the sequential order of filling in a many electron atom?

• A. $3s,3p,3d$
• B. $3d,4s,4p$
• C. $3d,4p,5s$
• D. $4p,4d,5s$

Answer 1

Answer: (C)

$3d,4p,5s$

Consider the options:-
A) Incorrect. After $3p$ is filled, $4s$ fills next not $3d$.
B) Incorrect. $4s$ fills before $3d$.
C) Correct. They all have same $n+l$ and they are in their increasing order of $n$.
D) Incorrect. $5s$ fills before $4d$.