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

Sodium metal crystallizes in bcc lattice with cell edge $=4.29<mspace\; width="1em"></mspace>\stackrel{0}{A}$. The radius of sodium atom will be-

(1) 1.50 $\stackrel{0}{A}$                                                 

(2) 1.86  $\stackrel{0}{A}$

(3) 2.80 $\stackrel{0}{A}$                                               

(4) None of these 

A metallic element exists as a cubic lattice. Each edge of the unit cell is 2.88 $\stackrel{0}{A}$. The density of the metal is 7.20 g $c{m}^{-3}$. How many unit cell will be present in 100 g of the metal -

(1) $6.85\times {10}^2$                             

(2) $5.82\times {10}^{23}$

(3) $4.37\times {10}^5$                             

(4) $2.12\times {10}^6$

Fraction of total volume occupied by atoms in a simple cube is-

(A) $\frac{\mathrm{\pi }}{2}$                                   

(B) $\frac{\sqrt{3}\mathrm{\pi }}{8}$

(C) $\frac{\sqrt{2}\mathrm{\pi }}{6}$                             

(D) $\frac{\mathrm{\pi }}{6}$

Analysis shows that an oxide ore of  nickel has formula  Ni_0.98O_1.00. The percentage of nickel as Ni³⁺ ions is nearly

1. 2

2. 96

3. 4.08

4. 98

Frenkel defect is not found in the halides of alkali metals because alkali metals have

1. high electropositivity

2. high ionic radii

3. high reactivity

4. ability to occupy interstitial sites

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

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