Question 93

Solution

If a triangular void pointing up in one close-packed layer is covered by a triangular void pointing down in the adjacent layer, then a void surrounded by six spheres results Such a void is called an octahedral void since the six spheres surrounding it lie at the corners of a regular octahedron.

octahedral void

octahedral void

Question 94

Solution

In a cubic unit cell,there are 8 vertex, 12 edges, 6 faces and one body centre.

Question 95

Solution

In AgI, if there are nI^{-} ions, there will be nAg^{+} ions. As I^{-} ions form the lattice, number of tetrahedral voids = 2n.

As there are nAg^{+} ions to occupy these voids, therefore fraction of tetrahedral voids occupied by Ag+ ions = n/2n = ½ = 50%.

As there are nAg

Question 96

Solution

For every atom in a close packed structure, there are two tetrahedral voids.

_{2}

Let the number of close packed spheres be N, then:

The number of octahedral voids generated = N

The number of tetrahedral voids generated = 2N