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

The most efficient packing of similar spheres is obtained in

(1) the simple cubic system and the body-centered cubic system

(2) the simple cubic system and the hexagonal close packed system

(3) the face centered cubic system and the hexagonal close packed system

(4) the body centered cubic system and the face centered cubic system

Copper metal has a face-centered cubic structure with the unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal. The apparent radius of a copper ion is-

(A) 0.128                                         

(B) 1.42

(C) 3.22                                           

(D) 4.22