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

In case of a semiconductor, which of the following statement is wrong 

(1) Doping increases conductivity

(2) Temperature coefficient of resistance is negative

(3) Resisitivity is in between that of a conductor and insulator

(4) At absolute zero temperature, it behaves like a conductor

Energy bands in solids are a consequence of

1. Ohm’s Law

2. Pauli’s exclusion principle

3. Bohr’s theory

4. Heisenberg’s uncertainty principle

In a P-type semiconductor

(1) Current is mainly carried by holes

(2) Current is mainly carried by electrons

(3) The material is always positively charged

(4) Doping is done by pentavalent material

At ordinary temperatures, the electrical conductivity of semi conductors in  mho/meter is in the range 
(1)${10}^{-3}$ to ${10}^{-4}$            

(2)${10}^6$ to ${10}^9$

(3) ${10}^{-6}$ to  ${10}^{-10}$         

(4) ${10}^{-10}$ to ${10}^{-16}$

 In a P-type semiconductor, germanium is doped with

(1) Boron                     

(2) Gallium

(3) Aluminium             

(4) All of these