Question

in which of the following structures coordination number for cations and anions in the packed structure will be same ?
A. `Cl^(-)` ions form fee lattice and `Na^(+)` ions occupy all octahedral voids of the unif cell
B. `Ca^(2+)` ions form fee lattice and `F^(-)` ions ooltipy all the eight tetrahedral voids of the unit cell
C. `O^(2)` ions form fee lattice and `Na^(+)` ions coccupy all the eight tetrahedral voids of the unit cell
D. `S^(2-)` ions form fee lattice and `Zn^(2+)` ions go into alternative tetrahedral voids of the unit cell

Answer 1

Correct Answer - A
NaCl crystal have rock salt structure having fee 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 `Na^(+)=6`
coordination n umber of `=Cl^(-)=6`