the number of tetrahedral voids per unit cell in NaCl crystal is ………… .

Options

A. 4
B. 8
C. Twice the number of octahedral voids.
D. Four times the number of octahedral voids.

Answer

A, C

Explanation

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.