Select the correct option based on statements below:

Assertion (A):	Semiconductors are solids with conductivities in the range from 10-6 — 104 ohm-1 m-1.
Reason (R):	Intermediate conductivity in semiconductors is due to a partially filled valence band.

 

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	(A) is false but (R) is true.

Match the type of packing given in Column I with the items given in Column II.

Codes

Match the items given in Column I with the items given in Column II.

Codes

Match the types of defects given in Column I with the statement given in Column II.

Codes

Match the defects given in Column I with the statements given in Column II.

Codes

Correct statement among the following regarding conductivity in solids is -

1.   ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace>\gg <mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace><<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}$

2.   ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace>\ll <mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace><<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}$

3.   ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace>,<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}<mspace\; width="1em"></mspace>><mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace>=<mspace\; width="1em"></mspace>\mathrm{zero}$

4.  ${\mathrm{\kappa }}_{\mathrm{metals}}<mspace\; width="1em"></mspace><<mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{semiconductors}}<mspace\; width="1em"></mspace>><mspace\; width="1em"></mspace>{\mathrm{\kappa }}_{\mathrm{insulators}}<mspace\; width="1em"></mspace>\ne <mspace\; width="1em"></mspace>\mathrm{zero}$

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

A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:

The incorrect statement among the following is:

Doping causes-

1. Dislocation defect.

2. Schottky defect.

3. Frenkel defect.

4. Electronic defect.