Q. Which of the following isoelectronic ions has lowest ionisation energy?
A) $Cl^{-}$
B) $Ca^{2 +}$
C) $K^{+}$
D) $S^{2 -}$
Explanation
(d)
$S^{2 -}$ has the largest size and hence, has the lowest ionisation energy
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.