The composition of a sample of Wusitite is ${\mathrm{Fe}}_{0.93}\mathrm{O}$. What is the percentage of the iron present as ${\mathrm{Fe}}^{3+}$ in total iron?

1. 15.05%

2. 25%

3. 35%

4. 45%

KCl crystallizes in the same type of lattice as does NaCl. Given that ${{\mathrm{r}}_{\mathrm{Na}}}^{+}/{{\mathrm{r}}_{\mathrm{cl}}}^{-}$ = 0.50 and ${{\mathrm{r}}_{\mathrm{Na}}}^{+}/{{\mathrm{r}}_{\mathrm{k}}}^{+}$ = 0.70, calculate the ratio of the side of the unit cell for KCI to that for Nacl:

1. 1.143

2. 1.224

3. 1.414

4. 0.875

Which of the following defects does the KBr show?

1. Frenkel

2. Schottky

3. Metal excess

4. Metal deficiency

An element X (At. Wt = 80 g/mol) having fcc structure, calculate no. of unit cells in 8 gm of X:

1. 0.4 X ${\mathrm{N}}_{\mathrm{A}}$

2. 0.1 X ${\mathrm{N}}_{\mathrm{A}}$

3. 4 X ${\mathrm{N}}_{\mathrm{A}}$

4. None of these

Triclinic crystal has the following unit cell parameters:

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 $\ne$ b $\ne$ c; $\mathrm{\alpha }$ $\ne$ $\mathrm{\beta }$ $\ne$ $\mathrm{\gamma }$ $\ne$ 90°

4. a = b $\ne$ c; $\mathrm{\alpha }$ = $\mathrm{\beta }$ = 90°, $\mathrm{\gamma }$ = 120°

A metal crystallizes in two cubic phases, face centred cubic (fcc) and body centred cubic (bcc) whose unit cell length are 3.5 and 3.0 Å respectively. Calculate the ratio of density of fcc and bcc. 

(1) 2.123                                     

 (2) 1.259

(3) 5.124                                       

(4) 3.134

In an f.c.c. unit cell, atoms are numbered as shown below. The atoms not touching each other are (Atom numbered 3 is face centre of front face).

(A) 3 & 4                                               

(B) 1 & 3 

(C) 1 & 2                                               

(D) 2 & 4

In a face centred cubic arrangement of metallic atoms, what is the relative ratio of the sizes of tetrahedral and octahedral voids ?

(1) 0.543                                   

(2) 0.732

(3) 0.414                                   

(4) 0.637

Close packing is maximum in the crystal which is-

(1) Simple cube                               

(2) bcc

(3) fcc                                             

(4) None

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