Iodine crystals are classified as-

1. Metallic solids.                                  

2. Ionic solids.

3. Molecular solids .                                 

4. Covalent solids.

A solid PQ have rock salt type structure in which Q atoms are at the corners of the unit cell. If the body centred atoms in all the unit cells are missing, the resulting stoichiometry will be-

(A) PQ                                               

(B) $P{Q}_2$

(C) $P_3{Q}_4$                                             

(D) $P_4{Q}_3$

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

(1) applying pressure

(2) increasing temperature

(3) both (a) and (b)

(4) none of these

At room temperature, sodium crystallizes in a body-centered cubic cell with a 4.24 $\stackrel{0}{A}$. The theoretical density of sodium is- (Atomic mass of sodium=23.0 g $mo{l}^{-1}$)

(A) $2.05<mspace\; width="1em"></mspace>g<mspace\; width="1em"></mspace>c{m}^{-3}$                                         

(B) $3.45<mspace\; width="1em"></mspace>g<mspace\; width="1em"></mspace>c{m}^{-3}$

(C) $1.00<mspace\; width="1em"></mspace>g<mspace\; width="1em"></mspace>c{m}^{-3}$                                         

(D) $3.55<mspace\; width="1em"></mspace>g<mspace\; width="1em"></mspace>c{m}^{-3}$

Which is amorphous solids-

(1) Rubber                                       

(2) Plastic

(3) Glass                                         

(4) All

In the unit cell of an fcc system, the number of octahedral and tetrahedral holes are

(1) 4,4                                                 

(2) 4, 8

(3) 1, 8                                             

(4) 4, 1

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

The unit cell of a metallic element of atomic mass 108 and density 10.5 g/$c{m}^2$ is a cube with edge length of 409 pm. The structure of the crystal lattice is-

(1) fcc                                                         

(2) bcc

(3) hcp                                                       

(4) None of these

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. ${\mathrm{ABC}}_3$

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, $\mathrm{\alpha }= \mathrm{\beta }= 90°,$ $\mathrm{\gamma }\ne 90°$