A mineral consists of a cubic close-packed structure formed by `O^(2-)` ions where half the octahedral voids are occupied by `Al^(3+)` and one eighth of the tetrahedral voids are occupied by `Mn^(2+)`. The chemical formula of the mineral is

Options

A. `Mn_(3)Al_(2)O_(3)`
B. `MnAl_(2)O_(3)`
C. `MnAl_(4)`
D. `Mn_(2)Al_(2)O_(5)`

Answer

B

Explanation

No. of `O^(-2)` per unit cell `= 8 xx 1/8 + 6 xx 1/2 = 4`
No. of `Al^(+3)` per unit cell = `4 xx 1/2 = 2`
No. of `Mn^(+2)` per unit cell `= 8 xx 1/8 = 1`
`MnAl_(2)O_(3)`