Compute the percentage void space per unit volume of unit cell in zinc fluoride structure.

1. 15.03%

2. 22.18%

3. 18.23%

4. 25.07%

8 : 8 co-ordination of CsCl is found to change into 6 : 6 co-ordination on:

1. Applying pressure.

2. Increasing temperature.

3. Both 1 and 2.

4. None of these.

The elements of symmetry in a crystal are:-

1. Plane of symmetry

2. Axis of symmetry

3. Centre of symmetry

4. All of the above

For a solid with the following structure, the co-ordination number of the point B is:

1. 3

2. 4

3. 5

4. 6

TiO₂ is a well-known example of:

1. Triclinic system.

2. Tetragonal system.

3. Monoclinic system.

4. None of the above.

How many octahedral and tetrahedral holes are present per unit cell in a face centred cubic arrangement of atoms?

1. 8,4

2. 1,2

3. 4,8

4. 2 ,1

The density of KCl is 1.9893 g cm^-3 and the length of a side unit cell is 6.29082 Å as determined by X-ray diffraction. The value of Avogadro’s number calculated from this data is:-

1. 6.017 x 10²³

2. 6.023 x 10²²

3. 7.03 x 10²³

4. 6.01 x 10¹⁹

Frenkel defect is noticed in:

1. AgBr

2. ZnS

3. Agl

4. All of the above

Close packing is maximum in the crystal lattice of:

1. simple cubic

2. face centred

3. body centred

4. none of these

A spinel is an important class of oxides consisting of two types of metal ions with the oxide ions arranged in ccp layers. The normal spinel has 1/8^th of the tetrahedral void occupied  by one type of metal and one half of the octahedral voids occupied by another type of metal ions. Such a spinel is formed by Zn²⁺, Al³⁺ and O^2- with Zn²⁺ in tetrahedral void. Give the simplest formula of the spinel.

1. ZnAl₂O₄

2. ZnAl₂O₃

3. ZnAlO

4. None of these