Question

The number of tetrahedral voids per unit cell in NaCl crystal is (c) twice the number of octahedral voids (d) four times the number of octahedral voids

Answer 1

(b, c) NaCl has fee arrangement of CF ions. Thus, Number of CF ions in packing per unit cell = 4 Number of tetrahedral voids = 2 x No. of particles present in close packing =24=8 Number of tetrahedral voids = 2 x No. of octahedral voids