In a crystalline solid, having formula `AB_(2)O_(4)` oxide ions are arranged in cubic close packed lattice while cations A are present in tetrahedral voids and cations B are present in octahedral voids.
(a) What percentage of the tetrahedral voids is occupied by A?
(b) What percentage of the octahedral voids is occupied by B ?

Options

A. `45.5%, 13.0%`
B. `50%, 12.5%`
C. `13.0%, 45.5 %`
D. `12.5%, 50%`

Answer

D

Explanation

In ccp arrangement of oxide ions, there are two tetrahedral voids and one octahedral void for each oxide ion.
For four oxide there will be eight tetrahedral voids and four octahedral voids. Out of these, two are accupied by B.
`%` of tetrahedral voids occupied by A
`=1/8xx100=12.5%`
`%` of octahedral voids occupied by B
`=2/4xx100=50.0%`