The number of tetrahedral voids in the unit cell of a face-centred cubic lattice of similar atoms is

In face centered cubic unit cell (FCC), tetrahedral voids are present on body diagonals. There are two tetrahedral voids on each body diagonal at $\left(\frac{1}{4}\right)$th of the distance from each corner.

So, total number of tetrahedral voids = (no. of tetrahedral voids per body diagonal) x (no. of body diagonals) = 2×4=8