If a solid `A^(o+)B^(ɵ)` having `ZnS` Structure is heated so that the ions along two of the axis passing throgh the face centre particles are lost and bivalent ion `(Z)` enters herre to maintain the electrical neutrality, so that the new formula unit becomes `A_(x)B_(y)C_(c)`, report the value of `x + y + c`.
Correct Answer – 7
For `ZnS` structure, (`Z_(eff)` of `ZnS = 4`)
Number of `B^(ɵ) = 4//”unit cell” (“corner” + “face centre”)`
Number of `A^(o+) = 4//”unit cell”` (in alternate TVs)
Number of `B^(o-)` ion removed
`= 4` (Two from each face centre)
`xx 1/2` (per face centre share) `= 2`
Number of `Br^(ɵ)`ions left `= 4 – 2 = 2//”unit cell”`
Number of `Z^(2-)` ions entering in place of `B^(ɵ) = 1`.
[To maintain electrical neutrality, `2 B^(ɵ) = 1 Z^(2)`]
Formula `= A_(4)B_(2)Z_(`1)`
`:. x + y + c = 4 + 2 + 1 = 7`