Q. Which set of characteristics of $ZnS$ crystal is correct?
A) Coordination number (4 : 4): ccp; $Zn^{2 +}$ ion in the alternate tetrahedral voids
B) Coordination number (6 : 6); hcp; $Zn^{2 +}$ ion in all tetrahedral voids
C) Coordination number (6 : 4); hcp; $Zn^{2 +}$ ion in all octahedral voids
D) Coordination number (4 : 4); ccp; $Zn^{2 +}$ ion in all tetrahedral voids
Explanation
(a)
$ZnS$ has zinc blende type structure ($i.e.,$ ccp structure). The $S^{2 -}$ ions are present at the corners of the cube and at the centre of each face. Zinc ions occupy half of the tetrahedral sites. Each zinc ion is surrounded by four sulphide ions which are disposed towards the corner of regular tetrahedron. Similarly, $S^{2 -}$ ion is surrounded by four $Zn^{2 +}$ ions.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.