Question

Which pair has identical electron configurations?

Answer 1

Identical electron configurations : K⁺ and Cl⁻

Further explanation  

In an atom, there are levels of energy in the shell and sub-shell  

This energy level is expressed in the form of electron configurations.  

Charging electrons in the sub-shell uses the following sequence:  

1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², etc.  

• S²⁻ and CI

S²⁻ : [Ne] 3s²3p⁶

Cl : [Ne] 3s²3p⁵

• K⁺ and CI⁻

K⁺ : 1s² 2s² 2p⁶ 3s² 3p⁶

Cl⁻ : 1s² 2s² 2p⁶ 3s²3p⁶

• S and Ar

S :[Ne] 3s²3p⁴

Ar : [Ne] 3s²3p⁶

• Cl⁻ and K

Cl⁻ : 1s² 2s² 2p⁶ 3s²3p⁶

K : 1s² 2s² 2p⁶ 3s² 3p⁶4s¹