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

(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