Why does chromium have configuration of type `3d^(5) 4s^(1)` instead of `3d^(4) 4s^(2)` ?

Explain why (i) the three electrons present in 2p subshell nitrogen remain unpaired. (ii) in potassium, the 19th electron enters into 4s subshell instead of 3d subshell, (iii) chromium has configuration 3d^(5) 4s^(1) instead of 3d^(4), 4s^2, (iv) the electronic configuration of zinc can be represented as [Ar] 3d^(10) 4s^(2)?

Assertion : The outer electronic configuration of Cr and Cu are 3d^(5) 4s^(1) and 3d^(10) 4s^(1) respectively . Reason : Electrons are filled in orbitals in order of increasing energies given by (n+l) rule.

The electronic configuration of valence shell of Cu is 3d^(10)4s^(1) and not 3d^(9)4s^(2) . How is this configuration explained?

The outer electronic configuration of the ground state chromium atom is 3d^(4),4s^(2)

Outer electronic configuration of Cu is ul(3d^9) ul (4s^2) .

The outer electronic configuration of the ground state chromium atom is 3d^(2),4s^(2) .

The outermost shell electronic configuration 3d^(5), 4s^(2) represents

The electronic configuration of an element is 1s^(2) 2s^(2) 2p^(6)3s^(2) 3p^(6) 4s^(2) 3d^(10) 4p^(2) . What is the atomic number of the element which is just below the above element in the periodic table ?

Statement-I : The ground state configuration of Cr is 3d^(5) 4s^(1) . Because Statement-II : A set of exactly half filled orbitals containing parallel spin arrangement provide extra stability.

Statement-I : The ground state configuration of Cr is 3d^(5) 4s^(1) . Because Statement-II : A set of exactly half filled orbitals containing parallel spin arrangement provide extra stability.