Question

The order of filling of electrons in the orbitals of an atom will be :

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

Answer 1

The correct option is B 4s, 3d, 5s, 4d

using $n+l$ rule

$3d\Rightarrow 3+2=5$

$4s\Rightarrow 4+0=4$

$4p\Rightarrow 4+1=5$

$4d\Rightarrow 4+2=6$

$5s\Rightarrow 5+0=5$

$4s,3d,4p,5s,4d$

$4s,3d,5s,4d$

option B is correct.