• question_answer The order of magnitude of ionic radii of ions $N{{a}^{+}},M{{g}^{2+}},A{{l}^{3+}}$ and $S{{i}^{4+}}$ is [MP PMT 1996] A) $N{{a}^{+}}<M{{g}^{2+}}<A{{l}^{3+}}<S{{i}^{4+}}$ B) $M{{g}^{2+}}>N{{a}^{+}}>A{{l}^{3+}}>S{{i}^{4+}}$ C) $A{{l}^{3+}}>N{{a}^{+}}>S{{i}^{4+}}>M{{g}^{2+}}$ D) $N{{a}^{+}}>M{{g}^{2+}}>A{{l}^{3+}}>S{{i}^{4+}}$

$N{{a}^{+}}>M{{g}^{2+}}>A{{l}^{3+}}>S{{i}^{4+}}$. All are isoelectronic but nuclear charge per electron is greatest for $S{{i}^{4+}}$. So it has smallest size and nuclear charge per electron for $N{{a}^{+}}$ is smallest. So it has largest size.