A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:

1.	All the domains get oriented in the direction of the magnetic field.
2.	All the domains get oriented in the direction opposite to the direction of the magnetic field.
3.	Domains get oriented randomly.
4.	Domains are not affected by the magnetic field.

The correct order of the packing efficiency in different types of unit cells is-

1.  Fcc < Bcc < Simple cubic

2.  Fcc > Bcc > Simple cubic

3.  Fcc < Bcc > Simple cubic

4.  Bcc < Fcc > Simple cubic

Dislocation defect is also known as-

1. Frenkel defect.

2. Schottky defect.

3. Non-stoichiometric defect.

4. Simple interstitial defect.

In the cubic close packing, the unit cell has ......... .

The edge lengths of the unit cells in terms of the radius of spheres constituting fcc, bcc, and simple cubic unit cells are respectively -

1. $2\sqrt{2\mathrm{r}}, \frac{4\mathrm{r}}{\sqrt{3}}, 2\mathrm{r}$

2. $\frac{4\mathrm{r}}{\sqrt{3}}, 2\sqrt{2\mathrm{r}}, 2\mathrm{r}$

3. $2\mathrm{r}, 2\sqrt{2\mathrm{r}}, \frac{4\mathrm{r}}{\sqrt{3}}$

4. $2\mathrm{r}, \frac{4\mathrm{r}}{\sqrt{3}}, 2\sqrt{2\mathrm{r}}$

Correct statement among the following regarding conductivity in solids is -

1.   ${\mathrm{\kappa }}_{\mathrm{metals}} \gg {\mathrm{\kappa }}_{\mathrm{insulators}} < {\mathrm{\kappa }}_{\mathrm{semiconductors}}$

2.   ${\mathrm{\kappa }}_{\mathrm{metals}} \ll {\mathrm{\kappa }}_{\mathrm{insulators}} < {\mathrm{\kappa }}_{\mathrm{semiconductors}}$

3.   ${\mathrm{\kappa }}_{\mathrm{metals}} , {\mathrm{\kappa }}_{\mathrm{semiconductors}} > {\mathrm{\kappa }}_{\mathrm{insulators}} = \mathrm{zero}$

4.  ${\mathrm{\kappa }}_{\mathrm{metals}} < {\mathrm{\kappa }}_{\mathrm{semiconductors}} > {\mathrm{\kappa }}_{\mathrm{insulators}} \ne \mathrm{zero}$

Incorrect(s) statement among the following:

1. (I, II)

2. (II, III)

3, (III, IV)

4. (I, IV)

Consider the following statements about semiconductors.

1. I and II

2. II and III

3. III and IV

4. I and IV

The incorrect statement among the following is:

Silicon doped with electron rich impurity forms -

1. p-type semiconductor.

2. n-type semiconductor.

3. Intrinsic semiconductor.

4. Insulator.