Question

$K^{+},{Cl}^{-},{Ca}^{2+},S^{2-}$ ions are isoelectronics. The decreasing order of their size is:

• A. $S^{2-}>{Cl}^{-}>K^{+}>{Ca}^{2+}$
• B. ${Ca}^{2+}>K^{+}>{Cl}^{-}>S^{2-}$
• C. $K^{+}>{Cl}^{-}>{Ca}^{2+}>S^{2-}$
• D. ${Cl}^{-}>S^{2-}>{Ca}^{2+}>K^{+}$

Answer 1

The correct option is A $S^{2-}>{Cl}^{-}>K^{+}>{Ca}^{2+}$

$K^{+},{Cl}^{-},{Ca}^{2+},S^{2-}$ ions are isoelectronics. The decreasing order of their size is $S^{2-}>{Cl}^{-}>K^{+}>{Ca}^{2+}$.The size of isoelectronics decreases with increase in atomic number. Atomic number of $S,Cl,K,Ca$ are $16,17,19$ and $20$respectively.