An example of amorphous solid among the following is -

1. Graphite (C)

2. Quartz glass (SiO₂)

3. Chrome alum

4. Silicon carbide (SiC)

Which of the following arrangements shows the schematic alignment of magnetic moments of antiferromagnetic substances? 

1. $\overline{)\uparrow }$ $\overline{)\uparrow }$ $\overline{)\uparrow }$ $\overline{)\uparrow }$ $\overline{)\uparrow }$ $\overline{)\uparrow }$

2. $\overline{)\downarrow }$ $\overline{)\downarrow }$ $\overline{)\downarrow }$ $\overline{)\downarrow }$ $\overline{)\downarrow }$ $\overline{)\downarrow }$

3. $\overline{)\uparrow }$ $\overline{)\uparrow }$ $\overline{)\downarrow }$ $\overline{)\uparrow }$ $\overline{)\uparrow }$ $\overline{)\downarrow }$

4. $\overline{)\uparrow }$ $\overline{)\downarrow }$ $\overline{)\uparrow }$ $\overline{)\downarrow }$ $\overline{)\uparrow }$ $\overline{)\downarrow }$

Incorrect statement among the following about amorphous solids is -

Schottky defect is observed in crystals when:

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 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.

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