Which of the following is not a characteristic of amorphous solids?

1. have sharp melting point

2. have non-orderly or very short-range orderly arrangement

3. show isotropy

4. have tendency to undergo irregular cleavage

Which type of solids here are generally good conductors of electricity?

1. metallic

2. covalent

3. ionic

4. molecular

Out of seven crystal systems how many can have body-centred unit cell?

1. 4

2. 2

3. 3

4. 5

In which of the following crystal systems the endcentred unit cell exists?

1. monoclinic

2. triclinic

3. cubic

4. all of these

If A, B, C are unequal and $\mathrm{\alpha }, \mathrm{\beta }, \mathrm{\gamma }$ are unequal and not $90°$, it represents a

1. triclinic system

2. tetragonal

3. monoclinic

4. orthorhombic

The empty space left in a hexagonal close packing of spheres in three dimensions is

1. 64%

2. 26%

3. 14%

4. 52.4%

The void formed by closed packed array of spheres located at the alternate corners of each face is

1. octahedral void

2. tetrahedral void

3. triangular void

4. both 1 and 2

A drop of liquid acquires a spherical shape because of

1. its tendency to maximize its surface area

2. its tendency to acquire minimum surface area

3. its viscous nature

4. none of these

Liquefied metals contain

1. metal anions only

2. metal cations only

3. metal kernels and mobile electrons

4. metal atoms only

Which of the following is the correct relation between enthalpy of vaporization (Joule/mole) and boiling point of a liquid?

1. $∆\mathrm{H}=1.5 {\mathrm{P}}_{\mathrm{b}}$

2. $∆\mathrm{H}=77 {\mathrm{T}}_{\mathrm{b}}$

3. $∆\mathrm{H}=88 {\mathrm{T}}_{\mathrm{b}}$

4. $∆\mathrm{H}=0.5 {\mathrm{T}}_{\mathrm{b}}$