Graphite is a good conductor of electricity due to the presence of ......... .

(1) Lone pair of electrons.

(2) Free valence electrons.

(3) Cations.

(4) Anions.

 

Graphite cannot be classified as ...........

1.  Conducting solid.

2.  Network solid.

3.  Covalent solid.

4.  Ionic solid.

Cations are present in the interstitial sites in ............ .

1.  Frenkel defect.

2.  Schottky defect.

3.  Vacancy defect.

4.  Metal deficiency defect.

Schottky defect is observed in crystals when:

Chargewise p-type semiconductor is -

1. Positive.

2. Neutral.

3. Negative.

4. Depends on the concentration of p impurity.

To get a n-type semiconductor from silicon, it should be doped with a substance with valency -

1.  2

2.  1

3.  3

4.  5

The total number of tetrahedral voids in the face centered unit cell is -

1. 6

2. 8

3. 10

4. 12

AgBr(s) crystals shows the following defect/s 

I. Schottky defect

II. Frenkel defect

III. Metal excess defect

IV Metal deficiency defect

1.  I and II

2.  III and IV

3.  I and III

4.  II and IV

The most efficient packing is present in -

1. HCP and BCC

2. HCP and CCP

3. BCC and CCP

4. BCC and Simple cubic cell

The percentage of empty space in a body centred cubic arrangement is ......... .

1.  74

2.  68

3.  32

4.  26