Question

Which one of the following sets of ions represents a collection of isoelectronic species ? 
(Given : Atomic Number : \(F : 9, Cl : 17, Na =11, Mg =12, Al =13, K =19, Ca =20, Sc =21\))

• A. \(N ^{3-}, O ^{2-}, F ^{-}, S ^{2-}\)
• B. \(K ^{+}, Cl ^{-}, Ca ^{2+}, Sc ^{3+}\)
• C. \(Ba ^{2+}, Sr ^{2+}, K ^{+}, Ca ^{2+}\)
• D. \(Li ^{+}, Na ^{+}, Mg { }^{2+}, Ca ^{2+}\)

Hint:

For isoelectronic species, the number of electrons should be the same. Calculate the number of electrons for each ion by considering the atomic number and the charge.

Answer 1

The Correct Option is B

Step 1: Understand Isoelectronic Species Isoelectronic species are atoms or ions that have the same number of electrons.
Step 2: Calculate the Number of Electrons in Each Ion
\(\text{Li}^+ \) (2 electrons), \(\text{Na}^+\) (10 electrons), \(\text{Mg}^{2+}\) (10 electrons), \(\text{Ca}^{2+}\) (18 electrons)
\(\text{Ba}^{2+}\) (54 electrons), \(\text{Sr}^{2+}\) (36 electrons), \(\text{K}^+\) (18 electrons), \(\text{Ca}^{2+}\) (18 electrons)
\(\text{N}^{3-}\) (10 electrons), \(\text{O}^{2-}\) (10 electrons), \(\text{F}^-\) (10 electrons), \(\text{S}^{2-}\) (18 electrons)
\(\text{K}^+\) (18 electrons), \(\text{Cl}^-\) (18 electrons), \(\text{Ca}^{2+}\) (18 electrons), \(\text{Sc}^{3+}\) (18 electrons)