Question

16) Which of the following represents an excited state configuration (i.e., one not a ground
state, but does not violate the Pauli principle)?
a. [Ar] 4s1 3d5
b. [Ar] 4s2 3d4
c. [Xe] 5s2 5p1
d. [Xe] 6s2 4f7

Answer 1

Ans b.[Ar] 4s²3d⁴

[Ar] 4s²3d⁴ is the excited state electronic configuration of Chromium (Ground state of Cr is [Ar] 4s¹3d⁵ because d⁵ is the half filled orbital which is stable),

According to Pauli's principle lower energy orbital should be filled first, so 4s should be filled first since it has lower energy than 3d.