Question

A $N{a^ + }$ ion is isoelectronic with:
 A. $L{i^ + }$
B. $M{g^{ + 2}}$
C. $C{a^{ + 2}}$
D. $B{a^{ + 2}}$

Answer 1

Hint: In order of the solution, first we should know the exact meaning or definition of Isoelectronic or for what it works. Then we compare each ion with $N{a^ + }$ ion, whether other ions is isoelectronic with $N{a^ + }$ or not.

Complete step-by-step answer:
Isoelectronic means different element or element ions containing the same number of electrons with them or in other words we can say that different ions have the same electronic structure.
Now, compare number of electrons in each Element ions:-
In $N{a^ + }$, Its atomic number is 11 that means it contains 11electrons and it has one ionic charge:
So, the number of Electrons in $N{a^ + }$= 11-1=10 electrons.
In $L{i^ + }$, Its atomic number is 3 that means it contains 3electrons and it has one ionic charge:
So, the number of Electrons in $L{i^ + }$= 3-1=2 electrons.
In $M{g^{ + 2}}$, Its atomic number is 12 that means it contains 12electrons and it has two ionic charge:
So, the number of Electrons in $M{g^{ + 2}}$ = 12-2=10 electrons.
In $C{a^{ + 2}}$, Its atomic number is 20 that means it contains 20electrons and it has two ionic charge:
So, the number of Electrons in $C{a^{ + 2}}$ = 20-2=18 electrons.
In $B{a^{ + 2}}$, Its atomic number is 56 that means it contains 56electrons and it has two ionic charge:
So, the number of Electrons in $B{a^{ + 2}}$= 56-2=54 electrons.

Therefore, the number of electrons in $M{g^{ + 2}}$ is the same as the number of electrons in $N{a^ + }$ ion. Both ions have 10 electrons with them.
Hence, the correct option is (B) $M{g^{ + 2}}$.

Note: Due to isoelectronic relation between different elements, an isoelectronicity effect is observed when two or more molecules have the same structure or the same configuration. Isoelectronic species is expected to show useful consistency and predictability in their properties.