Atomic Structure - Result Question 58

####34. The correct ground state electronic configuration of chromium atom is

(a) $[Ar] 3 d^{5} 4 s^{1}$

(b) $[Ar] 3 d^{4} 4 s^{2}$

(c) $[Ar] 3 d^{6} 4 s^{0}$

(d) $[Ar] 4 d^{5} 4 s^{1}$

$(1989,1 M)$

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Answer:

Correct Answer: 34. (a)

Solution:

  1. $\operatorname{Cr}(24)=\underbrace{1 s^{2} 2 s^{2} 2 p^{6} 3 s^{2} 3 p^{6}} _{\operatorname{Ar}} 3 d^{5} 4 s^{1}$

The above configuration is exception to Aufbau’s principle.



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