In `BeO` (zinc blende structure), `Mg^(2+)` is introduced in available `TV` is. The coordination numbers of `Be^(2+)` and `Mg^(2+)` are, respectively,

Options

A. `8,8`
B. `6,6`
C. `4,4`
D. `8,6`

Answer

C

Explanation

In `ZnS`- type structure, anions from fcc and cations are present in alternate `TVs`
In `BeO`, Number of `O^(2-) =` Corner `+` Face centre
`= 1 + 3 = 4`
Number of `Be^(2+) = 4` (alternate TVs)
Number of `Mg^(2+)` introduced `= 4` (available `TV = 4`)
So `CN` of `Be^(2+)` and `Mg^(2+)` ion `= 4:4`