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

The energy band gap is maximum in

(1) Metals               

(2) Superconductors

(3) Insulators         

(4) Semiconductors

The process of adding impurities to the pure semiconductor is called 
(1) Drouping       

(2) Drooping

(3) Doping           

(4) None of these

To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like

(1) A conductor

(2) A P-type semiconductor

(3) An N-type semiconductor

(4) An insulator

Donor type impurity is found in 
(1) Trivalent elements       

(2) Pentavalent elements

(3) In both the above       

(4) None of these

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the 

(1) Variation of scattering mechanism with temperature

(2) Crystal structure

(3) Variation of the number of charge carriers with temperature

(4) Type of bond