Solid State

Sodium has body centred packing. Distance between two nearest atoms is 3.7 A. The lattice parameter is

1. 4.3 A
2. 3.0 A
3. 8.6 A
4. 6.8 A

Lithium metal crystallises in a body-centred cubic crystal. If the length of the side of the unit cell of lithium is 351 pm, the atomic radius of lithium will be

1. 151.8 pm
2. 75.5 pm
3. 300.5 pm
4. 240.8 pm

Copper crystallises in a face-centred cubic lattice with a unit cell length of 361 pm. What is the radius of copper atom in pm?

1. 157
2. 181
3. 108
4. 128

If the lattice parameter for a crystalline structure is 3.6 A, then the atomic radius in fcc crystal is

1. 2.92 A
2. 1.27 A
3. 1.81 A
4. 2.10 A

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