Question

In closest packing of atoms

• A. The size of tetrahedral voids is greater than that of the octahedral void.
• B. The size of tetrahedral void is smaller than that of the octahedral void.
• C. The size of tetrahedral void is equal to that of the octahedral void.
• D. The size of tetrahedral void may be larger or smaller than that of the octahedrak void depending upon the size of atoms.

Answer 1

Answer: (B)

The size of tetrahedral void is smaller than that of the octahedral void.

Answer 2

For tetrahedral voids

$\frac{r_{+}}{r_{-}} = 0.225,$

$r_{+} = 0.225r_{-}$ ..... (i)

Similarly for octahedral voids

$r_{+} = 0.414r_{-}$ .... (ii)

From equation (i) and (ii) it is clear that size of octahedral voids is larger than that of tetrahedral voids.