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

the answer for sodium is 0.186

the answer for rubidium is 0.251

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error