The correct statement(s) among the above is -

a.	The coordination number of a cation occupying a tetrahedral hole is 4.
b.	The coordination number of a cation occupying an octahedral hole is 6.
c.	In Schottky defect, the density of the lattice decreases.

1. a, b                                         

2. b, c

3. a, b, c                                     

4. a, c

The unit cell dimensions of a cubic lattice (edges a, b, c and the angles between them, α, β, γ) are : 

1. a = b = c, $\mathrm{\alpha }= \mathrm{\beta }= \mathrm{\gamma }= 90°$

2. a = b $\ne$c, $\mathrm{\alpha }= \mathrm{\beta }= \mathrm{\gamma }= 90°$

3. a = b = c, $\mathrm{\alpha }= \mathrm{\gamma }= 90°,$ $\mathrm{\beta }\ne 90°$

4. a $\ne$b $\ne$c, $\mathrm{\alpha }= \mathrm{\beta }= 90°,$ $\mathrm{\gamma }\ne 90°$

In a cubic unit cell, atom A is present at each corner, atom B at each face centre and atom C at the body centre. The simplest formula of the solid is :

1. ${\mathrm{AB}}_2\mathrm{C}$                                         

2. ${\mathrm{A}}_2\mathrm{BC}$

3. ${\mathrm{AB}}_3\mathrm{C}$                                         

4. ${\mathrm{ABC}}_3$

If Xenon crystallizes in face center cubic lattice and the edge of the unit cell is 620 pm, then the radius of the Xenon atom is-

1. 219.20 pm                                   

2. 438.5 pm

3. 265.5 pm                                     

4. 536.94 pm

Iodine crystals are classified as-

1. Metallic solids.                                  

2. Ionic solids.

3. Molecular solids .                                 

4. Covalent solids.

In calcium fluoride, having the fluorite structure, the coordination numbers for calcium ion (Ca²⁺) and fluoride ion (F^-) are:

1. 4 and 2

2. 6 and 6

3. 8 and 4

4. 4 and 8

The incorrect statement among the following is -

Iron exhibits bcc structure at room temperature. Above 900 °C, it transforms to fcc structure. The ratio of density of iron at room temperature to that at 900 °C is:

(Molar mass and atomic radii of iron remain constant with temperature) 

1. $\frac{\sqrt{3}}{\sqrt{2}}$

2. $\frac{4\sqrt{3}}{3\sqrt{2}}$

3. $\frac{3\sqrt{3}}{4\sqrt{2}}$

4. $\frac{1}{2}$

Iron has a body centred cubic unit cell with the cell dimension of 286.65 pm. Density of iron is 7.87 g cm^-3. The value of  Avogadro's number based on this data will be -

(Atomic mass of Fe = 56.0 u)

1. 6.04 x 10²³ mol^-1

2. 12.08 x 10²⁴ mol^-1

3. 6 x 10²² mol^-1

4. 6 x 10^-23 mol^-1