Incorrect statement among the following about amorphous solids is -

1.	On heating they may become crystalline at a certain temperature.
2.	They may become crystalline on keeping for a long time.
3.	Amorphous solids can be moulded by heating.
4.	They are anisotropic in nature.

Network solid, among the following, is :

1. SO₂(solid)

2. I₂

3. Diamond

4. H₂O(ice)

I. Mg(s)

II. TiO(s)

III. I₂(s)

IV. H₂O(s)

The insulator among the given examples is -

1. Only I

2. Only II

3. III and IV

4. II, III, and IV

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

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 incorrect statement among the following regarding hexagonal close packing is:

Same coordination number for cations and anions is present in: