Question

Which of the following is not iso electronic series

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Isoelectronic species are the species which have same number of electrons.
Lets check out number of electrons in each option.

(a)$C{l}^{-}\to 17+1=18electrons$

$P^{3-}\to 15+3=18electrons$ }Yes

$Ar\to 18electrons$

(b) $N^3\to 7+3=10electrons$

$Ne\to 10electrons$}Yes

$M{g}^{+2}\to 12-2=10electrons$

(c) $B^{+3}\to 5-3=2electrons$

$He\to 2electrons$}Yes

$L{i}^{+}\to 3-1=10electrons$

(d)

$S^2\to 16+2=18electrons$ ( $N^{3-}\to 7+3=10electrons$

$M{g}^{+2}\to 12-2=10electrons$ }