Question

In $N{a}_{2}O$ , having ant fluorite structure

• A. oxide ions have a cubic close packed arrangement and $N{a}^{+}$ occupy all the eight tetrahedral voids
• B. oxide ions have a cubic close packed arrangement and $N{a}^{+}$ occupy all the octahedral voids
• C. $N{a}^{+}$ ions have a cubic close packed arrangement and $O^{2-}$ occupy all the octahedral voids
• D. $N^{+}$ ions have a cubic close arrangement and $O^{2-}$ occupy all the tetrahedral voids

Answer 1

Answer: (A)

In antifluorite structure, $O^{2-}$ ions occupy half of the cubic holes and $N{a}^{+}$occupy all tetrahedral voids, eg, $N{a}_{2}O.$
$O^{2-}$ are surrounded by $8N{a}^{+}$ions and $N{a}^{+}$are surrounded by $40^{2-}$ ions.
So, it has $4:8$ coordination.