Question

Consider the ions : $ {{K}^{+}},\,{{S}^{2-}},C{{l}^{-}} $ and $ C{{a}^{2+}}. $ The radii of these ionic species follow the order

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

Answer 1

Ionic radii $ \propto \frac{1}{{{Z}_{eff}}} $ $ \propto \text{negative}\,\text{charge}\,\propto \frac{\text{1}}{\text{positive}\,\text{charge}} $ Thus, the correct order of ionic radii of these ions is $ {{S}^{2-}}>C{{l}^{-}}>{{K}^{+}}>C{{a}^{2+}} $