Question

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 units 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 $Zn^{2 +}$ions go into alternate tetrahedral voids of the unit cell.

Answer 1

Answer: (A)

$Cl^{-}$ions form fcc lattice and $Na^{+}$ions occupy all octahedral voids of the unit cell

Answer 2

In NaCl type unit cell, all cations and anions have a coordination number of 6.