31. A semi condutor in its purest form is called
a. Intrinsic semi-conductor
b. Extrinsic semi conductor
c. P-type semi-conductor
d. N-type semi-conductor

32. At absolute zero temperature a semi conductor behaves like
a. An insulator
b. A super-conductor
c. A good conductor
d. A variable resistor

33. An electron in the conduction band
a. Has highly energy than the electron in the valence band
b. Has lower energy then the electron in the valence band
c. loses its charge easily
d. jumps to the top of the crystal

34. When an electron breaks a covalent bond and moves aways
a. A hole is created
b. A proton is also lost
c. Atom becomes an ion
d. Rest of the electron move at a faster rate

35. The resistivity of a semi-conductor
a. Increases as the temperature increases
b. Decreases as the temperature increases
c. Remains constant even when temperature varies
d. None of the above

36. The process of deliberately adding impurity to a semi-conductor material is called
a. Impurification
b. pollution
c. Deionisation
d. Doping

37. A doped semi-conductor is called
a. Impure semi-conductor
b. Dipole semi-conductor
c. Bipolar semi-conductor
d. Extrinsic semi-conductor

38. Before doping the semi conductor material is
a. Dehydrated
b. Heated
c. Hardened
d. Purified

39. Which of the following is donor impurity element?
a. aluminium
b. Boron
c. Phosphorous
d. Indium

40. Which of the following is acceptor impurity element?
a. Aluminium
b. Gallium
c. Arsenic
d. Phosphorous