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.

The sharp melting point of crystalline solids is due to......... .

Iodine molecules are held in the crystals lattice by ........ .

1.  London forces.

2.  Dipole-dipole interactions.

3.  Covalent bonds.

4.  Coulombic forces.

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

Which of the following is not the characteristic of ionic solids?
 

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.

Which of the following oxides behaves as a conductor or insulator depending upon temperature?

1.  TiO

2.  SiO₂

3.  TiO₃

4.  MgO

Which of the following oxides shows electrical properties like metals?

1.  SiO₂

2.  MgO

3.  SO₂ (s)

4.  CrO₂

The lattice site in a pure crystal cannot be occupied by ......... .

1.  Molecule

2.  Ion

3.  Electron

4.  Atom