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

GaAs is 

(1) Element semiconductor

(2) Alloy semiconductor

(3) Bad conductor

(4) Metallic semiconductor

If ${\mathrm{n}}_{\mathrm{e}}$ and ${\mathrm{n}}_{\mathrm{h}}$ are the number of electrons and holes in a semiconductor heavily doped with phosphorus, then

(1) ${\mathrm{n}}_{\mathrm{e}}$>> ${\mathrm{n}}_{\mathrm{h}}$               

(2)  ${\mathrm{n}}_{\mathrm{e}}$<< ${\mathrm{n}}_{\mathrm{h}}$  

(3) ${\mathrm{n}}_{\mathrm{e}}$$\le$${\mathrm{n}}_{\mathrm{h}}$                 

(4) ${\mathrm{n}}_{\mathrm{e}}$ = ${\mathrm{n}}_{\mathrm{h}}$  

To obtain electrons as majority charge carriers in a semiconductor, the impurity mixed is 
(1) Monovalent         

(2) Divalent

(3) Trivalent               

(4) Pentavalent

For germanium crystal, the forbidden energy gap in joules is

(1) $1.12\times {10}^{-19}$        

(2) $1.76\times {10}^{-19}$

(3)  $1.6\times {10}^{-19}$         

(4) Zero

A pure semiconductor behaves slightly as a conductor at

(1) Room temperature             

(2) Low temperature

(3) High temperature               

(4) Both (b) and (c)

Which is the correct relation for the forbidden energy gap in the conductor, semiconductor, and insulator

(1) $∆{\mathrm{Eg}}_{\mathrm{c}}<∆{\mathrm{Eg}}_{\mathrm{insulator}}<∆{\mathrm{Eg}}_{sc}$

(2) $∆{\mathrm{Eg}}_{\mathrm{c}}<∆{\mathrm{Eg}}_{\mathrm{sc}}<∆{\mathrm{Eg}}_{\mathrm{insulator}}$

(3) $∆∆{\mathrm{Eg}}_{\mathrm{sc}}<∆{\mathrm{Eg}}_{\mathrm{insulator}}<{\mathrm{Eg}}_{\mathrm{c}}$

(4) $∆{\mathrm{Eg}}_{\mathrm{sc}}<∆Ec<∆{\mathrm{Eg}}_{\mathrm{insulator}}$

At room temperature, a P-type semiconductor has

(1) Large number of holes and few electrons

(2) Large number of free electrons and few holes

(3) Equal number of free electrons and holes

(4) No electrons or holes