Ncert Exercises & Solutions

The total number of tetrahedral voids in the face centered unit cell is -

1. 6

2. 8

3. 10

4. 12

HINT: The number of tetrahedral voids generated is 2N (N = number of close-packed spheres )

Explanation:

FCC unit cell contains 8 tetrahedral voids at the center of each 8 smaller cubes of a unit cell as shown below :

Number of atoms in FCC unit cell = 4

Number of octahedral voids = 4

Number of tetrahedral voids = 8