Test Index

Solid State

Section: Chemistry

Question : 9 of 19

Marks: +1, -0

The number of the nearest neighbours of an atom present in the topmost layer is $12$
The efficiency of atom packing is $74\%$
The number of octahedral and tetrahedral voids per atom are $1$ and $2$ , respectively
The unit cell edge length is $2\sqrt{2}$ times the radius of the atom

Solution:

CCP is ABC ABC ...... type packing

(A) In topmost layer, each atom is in contact with 6 atoms in same layer and 3 atoms below this layer.

Packing fraction

=\frac{\frac{4 \times 4}{3 \pi r^{2}}}{\left(\frac{4r}{\sqrt{2}}\right)^{2}}=(0.74)

Octahedral void = 4

Tetrahedral void = 8

(D)

4r = a\sqrt{2}

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