Solid State

Percentage of free space in a body centred cubic unit cell is

1. 34%
2. 28%
3. 30%
4. 32%

Which of the following statements is not correct?

1. The number of carbon atoms in a unit cell of diamond is 8
2. The number of Bravais lattices in which a crystal can be categorized is 14
3. The fraction of the total volume occupied by the atoms in a primitive cell is 0.48.
4. Molecular solids are generally volatile.

With which one of the following elements silicon should be doped so as to give p-type of semiconductor?

1. Selenium
2. Boron
3. Germanium
4. Arsenic

If a stands for the edge length of the cubic systems: simple cubic, body centred cubic and face centred cubic, then the ratio of radii of the spheres in these systems will be respectively

1. 12a : 32a : 22a
2. 1a : 3a : 2a
3. 12a : 34a : 12 2a
4. 12a : 3a : 1 2a

For a cubic crystal structure which one of the following relations indicating the cell characteristics is correct?

1. a b c and = = = 90
2. a = b = c and = 90
3. a = b = c and = = = 90
4. a b c and and = 90

The fraction of total volume occupied by the atoms present in a simple cubic unit cell is

1. 3 2
2. 4 2
3. 4
4. 6

If NaCl is doped with 10-4 mol% of SrCl2, the concentration of cation vacancies will be (NA = 6.02 1023 mol-1)

1. 6.02 1016 mol-1
2. 6.02 1017 mol-1
3. 6.02 1014 mol-1
4. 6.02 1015 mol-1

The appearance of colour in solid alkali metal halides is generally due to

1. interstitial positions
2. F-centres
3. Schottky defect
4. Frenkel defect

CsBr crystallises in a body centered cubic lattice. The unit cell length is 436.6 pm. Given that the atomic mass of Cs = 133 and that of Br = 80 amu and Avogadro number being 6.02 1023 mol-1, the density of CsBr is

1. 4.25 g/cm3
2. 42.5 g/cm3
3. 0.425 g/cm3
4. 8.25 g/cm3

Copper has face centered cubic (fcc) lattice with interatomic spacing equal to 2.54 A. The value of lattice constant for this lattice is

1. 2.54 A
2. 3.59 A
3. 1.27 A
4. 5.08 A

In a face-centered cubic lattice, a unit cell is shared equally by how many unit cells?

1. 2
2. 4
3. 6
4. 8

A compound formed by elements X and Y crystallizes in a cubic structure in which the X atoms are at the corners of a cube and the Y atoms are at the face-centers. The formula of the compound is :-

1. XY3
2. X3Y
3. XY
4. XY2

The pyknometric density of sodium chloride crystal is 2.165 103 kg m-3 while its X-ray density is 2.178 103 kg m-3. The fraction of unoccupied sites in sodium chloride crystal is

1. 5.96
2. 5.96 10-2
3. 5.96 10-1
4. 5.96 10-3

Number of atoms per unit cell in B.C.C. is

1. 9
2. 4
3. 2
4. 1

When Zn converts from melted state to its solid state, it has hcp structure, then find the number of nearest atoms.

1. 6
2. 8
3. 12
4. 4

The cations and anions are arranged in alternate form in

1. metallic crystal
2. ionic crystal
3. covalent crystal
4. semi-conductor crystal

Cations and anions combine in a crystal to form the following type of compound

1. ionic
2. metallic
3. covalent
4. dipole-dipole

In a cubic crystal, A-atoms are placed at every corner and B-atoms at the centre of every face. The formula of the compound is

1. AB
2. AB3
3. A2B2
4. A2B3