169. A semiconductor has ____ temperature coefficient of resistance
A. positive
B. zero
C. negative
D. none of the above
170. The most commonly used semiconductor is
A. germanium
B. silicon
C. carbon
D. sulphur
171. A semiconductor has generally _____ valence electrons.
A.2
B.3
C.6
D.4
172. The resistivity of pure germanium under standard conditions is about
A. 6 x 104 L2 cm
B. 3 x 104 Sr2 cm
C. 3 x 106 SI cm
D. 6 x 10-4 LI cm
173. When a pure semiconductor is heated, its 3V
A. goes up
B. goes down
C. remains the same
D. cannot say
174. The strength of a semiconductor crystal resistance comes from
A. forces between nuclei
B. forces between protons
C. electron-pair bonds
D. none of the above
175. When a penta valent impurity is added to a pure semiconductor, it becomes
A. an insulator
B. an intrinsic semiconductor
C. p-type semiconductor
D. n-type semiconductor
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