Question

Choose the correct answer form the alternatives given. $C{a}^{2+}$ is isoelectronic with:

• A. $Na$
• B. $4M{g}^{2+}$
• C. $B{a}^{2+}$
• D. $Ar$

Answer 1

Answer: (D)

$Ar$

The electronic configuration of Ca(Z=20) is $Ca={1s}^2{2s}^{2}2p^{6}3s^2{3p}^{6}4s^2$

while The electronic configuration of ${Ca}^{2+}$ is ${Ca}^{2+}={1s}^2{2s}^{2}2p^{6}3s^2{3p}^6$ = Ar

The no.of electrons in ${Ca}^{2+}$ is 18 after the loss of two electrons. So it has noble gas configuration of Ar.