In which of the following structures coordination number for cations and anions in the packed structure will be same
a. Cl – ions form fcc lattice and Na+ ions occupy all octahedral voids of the unit cell
b. Ca 2+ ions form fcc lattice and F – ions occupy all the eight tetrahedral voids of the unit cell
c. O 2- ions form fcc lattice and Na+ ions occupy all the eight tetrahedral voids of the unit cell
d. S 2- ions form fcc lattice and Zn2+ ions go into alternate tetrahedral voids of the unit cell
Ans.a
Explanation : NaCl crystal have rock salt structure having fcc lattice in which Cl– ions are present at fcc lattice points and face centre and Na + occupies all the octahedral void of given unit cell
Where, coordination number of Na + = 6
Coordination number or Cl – = 6
(20)