Ferric oxide crystalliczes in a hexagonal close packed array of oxide ions with two out of every three. Octuhedral holes occupied by ferric ions. The formula of the ferric oxide is

Options

A. FeO
B. `Fe_(3)O_(4)`
C. `Fe_(2)O_(3)`
D. `None of these

Explanation

Suppose the number of oxide ions `(O^(2-))` in the packing =N. No. of octahedral voids=N
As `2//3^(nd` of the octahedral voids are occupied by ferric ions, therefore, number of erric ions present `=(2)/(3)xxN=(2N)/(3)`
Therefore, ratio of `Fe^(3+),O^(2-)=(2N)/(3):N=2:3`
Hence 'C', the formula of ferric oxide is `Fe_(2)O_(3)`.