Question

In an ionic oxide, oxide ions are arranged in hcp array and positive ion occupy two thirds of octahedral voids. Suggest the formula assuming metal as M.

• A. $M_2{O}_3$
• B. $M_{2}O$
• C. $M_2{O}_4$
• D. $MO$

Answer 1

The correct option is A $M_2{O}_3$

Number of octahedral voids for each oxide ions $=1$
Given that $\frac{2}{3}$rd of octahedral voids are occupied by metal ions.
Thus, each oxide ion has $\frac{2}{3}$ metal ion or whole number ratio of oxide and metal ion is $1:\frac{2}{3}$ or $3:2$.

Thus, the formula is $M_2{O}_3$.