The number of tetrahedral voids per unit cell in \(NaCl\) crystal is___.

NaCl crystal

\(NaCl\) has face centered cubic packing.
For face centered cubic \((FCC)\) packing:

(A) Number of octahedral voids = Number of constituent particles forming the lattice.
(B) Number of tetrahedral voids \(= 2\) (number of octahedral voids)

And number of particles in one unit cell of \(FCC = 4\)

Therefore, number of octahedral voids \(= 4\)

And the number of tetrahedral voids \(= 2 \times 4 = 8\).

Hence, the options \((B)\) and \((C)\) are correct.