The coordination number of a square close-packed structure in two dimensions is -

1. 2

2. 3

3. 4

4. 6

Doping causes-

1. Dislocation defect.

2. Schottky defect.

3. Frenkel defect.

4. Electronic defect.

Silicon doped with electron rich impurity forms -

1. p-type semiconductor.

2. n-type semiconductor.

3. Intrinsic semiconductor.

4. Insulator.

The incorrect statement among the following is:

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

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.

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

Consider the following statements about semiconductors.

1. I and II

2. II and III

3. III and IV

4. I and IV