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

The charge on a hole is equal to the charge of

(1) Zero               

(2) Proton

(3) Neutron         

(4) Electron

Which of the following has negative temperature coefficient of resistance 
(1) Copper               

(2) Aluminium

(3) Iron                   

(4) Germanium

In semiconductors at a room temperature 

(1) The valence band is partially empty and the conduction band is partially filled

(2) The valence band is completely filled and the conduction band is partially filled

(3) The valence band is completely filled

(4) The conduction band is completely empty

Regarding a semiconductor which one of the following is wrong 

(1) There are no free electrons at room temperature

(2) There are no free electrons at 0 K

(3) The number of free electrons increases with rise of temperature

(4) The charge carriers are electrons and holes