The electron configuration of Ca+2 is most similar to that of?

The electron configuration of Ca⁺² is most similar to that of Ar(Argon)

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.  

Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d, and f. The maximum number of electrons for each sub-shell is  

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

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

Calcium (symbol Ca) is an alkaline earth metal element with an atomic number of 20, so the number of electrons is 20 (for neutral atoms)

The electron configuration of Ca :  [Ar] 4s² ⇒ 1s² 2s² 2p⁶ 3s²3p⁶4s²

For the Ca²⁺ cation, which has a +2 charge, it is obtained by removing 2 electrons, so that the electron configuration is the same as for the element Ar (argon): 1s² 2s² 2p⁶ 3s²3p⁶