A semiconductor is cooled from ${\mathrm{T}}_1\mathrm{K}$ to ${\mathrm{T}}_2\mathrm{K}$. Its resistance

(1) Will decrease

(3) Will increase

(3) Will first decrease and then increase

(4) Will not change

In intrinsic semiconductor at room temperature, the number of electrons and holes are

(1) Equal

(2) Zero

(3) Unequal

(4) Infinite

In a semiconductor, the separation between the conduction band and valence band is of the order of

(1) 100 eV

(2) 10 eV

(3) 1 eV

(4) 0 eV

The intrinsic semiconductor becomes an insulator at

(1) $0°\mathrm{C}$

(2) $-100°\mathrm{C}$ 

(3)  300 K

(4) 0 K

In a good conductor, the energy gap between the conduction band and the valence band is:
1. Infinite
2. Wide
3. Narrow
4. Zero

The impurity atom added to germanium to make it an N-type semiconductor is 

(1) Arsenic

(2) Iridium

(3) Aluminium

(4) Iodine

When N-type of semiconductor is heated

(1) Number of electrons increases while that of holes decreases

(2) Number of holes increases while that of electrons decreases

(3) Number of electrons and holes remains same

(4) Number of electrons and holes increases equally

To obtain a P-type germanium semiconductor, it must be doped with 

(1) Arsenic

(2) Antimony

(3) Indium

(4) Phosphorus

The temperature coefficient of resistance of a semiconductor

(1) Is always positive

(2) Is always negative

(3) Is zero

(4) Maybe positive or negative or zero

A P-type semiconductor is formed when- 
A. As impurity is mixed in Si
B. Al impurity is mixed in Si
C. B impurity is mixed in Ge
D. P impurity is mixed in Ge

(1) A and C

(2) A and D

(3) B and C

(4) B and D