question_answer

If the radii of \[M{{g}^{2+}},C{{s}^{\oplus }},{{O}^{2\Theta }},{{S}^{2\Theta }}\]and \[C{{l}^{\Theta }}\] ions are \[0.65,\] \[1.69,\] \[1.40,\]\[1.84,\] and \[1.81\text{ }\overset{o}{\mathop{A}}\,,\] respectively. The sum of coordination number of the cations in the crystals of \[CsCl,\text{ }MgS\]and \[MgO\]_______.

Answer:

18