Question

$Ca^{2+}$ is isoelectronic with:

• A. $Na^{+}$
• B. $Ar$
• C. $Mg^{2+}$
• D. $Kr$

Answer 1

Answer: (B)

$Ar$

Answer 2

$Ca ^{2+}(2,8,8)$ and $Ar(2,8,8)$ contain equal number (18) of electrons, hence they are iso-electronic.