Question

Which set of characteristics of ZnS crystal is correct?

• A. Coordination number (4: 4) ; cep ; $Zn^{2+}$ ions in the alternate tetrahedral voids
• B. Coordination number (6: 6); hep ; $Zn^{2+}$ ions in all tetrahedral voids
• C. Coordination number (6: 4); hep ; $Zn^{2+}$ ions in all octahedral voids
• D. Coordination number (6: 6); hep ; $Zn^{2+}$ ions in all octahedral voids

Answer 1

Answer: (A)

Coordination number (4: 4) ; cep ; $Zn^{2+}$ ions in the alternate tetrahedral voids

Answer 2

ZnS has ccp structure (fee) in which $S^{2-}$ ions occupy comers and face-centres and $Zn^{2+}$ ions are present in alternate tetrahedral voids. Further, each $Zn^{2+}$ ion is surrounded tetrahedrally by $4 \, S^{2-}$ ions and vice-versa.