इन इलेक्ट्रॉनिक विन्यासवाले तत्त्वों के नाम बताएँ।
`[Ar]3d^(5)4s^(2)`

(A) : The electronic configuration of Cr is [Ar]3d^(5)4s^(1) but not [Ar]3d^(4)4s^(2) (R) : Lowering energy with configuration [Ar]3d^(5) 4s^(1) is more than that with configuration [Ar]3d^(4)4s^(2)

(A) : The electronic configuration of Cr is [Ar]3d^(5) 4s^(1) but not [Ar]3d^(4) 4s^(2) (R) : Lowering energy with configuration [Ar]3d^(5)4s^(1) is more than that with configuration [A]3d^(4)4s^(2)

The rule that explains the reason for chromium to have [Ar]3d^(5)4s^(1) configuration instead of [Ar] 3d^(4)4s^(2) ?

The rule that explain the reason for chromium to have [Ar]3d^(5) 4s^(1) configuration instead of [Ar]3d^(4),4s^(2) is