Iron crystallizes in a b.c.c. system with a lattice parameter of 2.861 $\stackrel{0}{A}$. Calculate the density of iron in the b.c.c. system (Atomic weight of Fe = 56, $N_A=6.02\times {10}^{23}mo{l}^{-1}$)

(1) 7.92g $m{l}^{-1}$                                   

 

(2) 8.96g $m{l}^{-1}$

(3) 2.78g $m{l}^{-1}$                                     

(4) 6.72g $m{l}^{-1}$

An alloy of copper, silver, and gold is found to have copper constituting the ccp lattice. If silver atoms occupy the edge centers and gold is present at the body center, the alloy has a formula-

(1) $C{u}_{4}A{g}_{2}Au$                               

(2) $C{u}_{4}A{g}_{4}Au$

(3) $C{u}_{4}A{g}_{3}Au$                               

(4) $CuAgAu$

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) $2.05 g c{m}^{-3}$                                         

(B) $3.45 g c{m}^{-3}$

(C) $1.00 g c{m}^{-3}$                                         

(D) $3.55 g c{m}^{-3}$

Which is amorphous solids-

(1) Rubber                                       

(2) Plastic

(3) Glass                                         

(4) All

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

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

1. a, b                                         

2. b, c

3. a, b, c                                     

4. a, c

Among the following types of voids, which one is the largest void-

(1) Triangular system                             

(2) Tetragonal system

(3) Monoclinic system                             

(4) Octahedral

The n of a cubic unit cell is 4. The type of cell as-

(1) Body centred                               

(2) Face centred

(3) Primitive                                     

(4) None of these