In BCC, the distance between the two nearest atoms will be:

1. $\sqrt{3}$ $a$

2. $\frac{\sqrt{3}}{2}a$

3. $\frac{\sqrt{3}}{4}a$

4. $\frac{a}{2}$

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

Zn converts its melted state to its solid state. It has an HCP structure. The number of the nearest atom is:
1. 6
2. 8
3. 12
4. 4

MgO and NaCl has similar structure. In MgO, magnesium is surrounded by how many oxygen atoms?
1. 2
2. 4
3. 6
4. 1

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. X₃Y

2. XY

3. XY₂

4. XY₃

On the basis of unit cell concept a crystal has:

1. 7 systems
2. 14 systems
3. 230 systems
4. 32 systems

The number of atoms per unit cell in a BCC structure is:

1. 9

2. 4

3. 2

4. 1

The second order Bragg diffraction of X-rays with λ = 1.00 Å from a set of parallel planes in a metal occurs at an angle $60°$. The distance between the scattering planes in the crystal is:

1.  2.00 Å
2.  1.00 Å
3.  0.57 Å
4.  1.15 Å

The edge length of a face centered unit cubic cell is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is:
1. 144 pm
2. 398 pm
3. 288 pm
4. 618 pm

Schottky defect shows: