Question

The number of tetrahedral voids per unit cell in NaCl crystal is ……..
A. 4
B. 8
C. Twice the number of octahedral voids.
D. Four times the number of octahedral voids.

Answer 1

Correct Answer - A::C
NaCl has fcc arrangement of ` Cl^(-)` ions. Hence, number of `Cl^(-)` ions in packing per unit cell = 4.
NO. of tetrahdral voids is double the number of octahedral voids. Hence, tetrahedral voids = 4.