What is the ratio of number of atoms per unit cell to the number of T-voids in cubic close packing?

1 : 2

The correct answer is option 2. 1 : 2.

In Cubic closed packing, unit cell is of fcc type

(i) No. of atoms per unit cell = \(\frac{1}{8}\) x 8 + \(\frac{1}{2}\) x 6 = 1 + 3 = 4

(ii) No. of T-voids in a unit cell = 8

Ratio of (i) and (ii) is 4 : 8 or 1 : 2