Question

Which of the following sets does not represent isoelectronic species?

• A. $Ne , F^{-} , O ^{2-}$
• B. $Cl ^{-}, Ar , K ^{+}$
• C. $S ^{2-}, Br ^{-}, Kr$
• D. $Mg ^{2+}, Na ^{+}, Ne$

Answer 1

Answer: (C)

$Ne \Rightarrow 10 \,\,\,\,\,\,\,\,\,\,\, F \Rightarrow 9+1=10 \,\,\,\,\,\,\,\, O^{2-} \Rightarrow 8+2=10$

$Cl ^{-} \Rightarrow 17+1=18 \,\,\,\,\, Ar \Rightarrow 18 \,\,\,\,\,\,\, K ^{+} \Rightarrow 19-1=18$

$S^{2-} \Rightarrow 16+2=18 \,\,\,\,\, B r^{-} \Rightarrow 35+1=36 \,\,\,\,\,\,\, K r=36$

$Mg ^{2+} \Rightarrow 12-2=10 \,\,\,\,Na ^{+} \Rightarrow 11-1=10 \,\,\,\,\,\,\,\,\, Ne =10$