176.  Addition of pentavalent impurity to a semiconductor creates many
A. free electrons
B. holes
C. valence electrons
D. bound electrons

---

177. A pentavalent impurity has ___ valence electrons
A.3
B.5
C.4
D.6

---

178. An n-type semiconductor is
A. positively charged
B. negatively charged
C. electrically neutral
D. none of the above

---

179.  A trivalent impurity has electrons.
A.4
B.5
C.6
D.3

---

180. Addition of trivalent impurity to a semiconductor creates many
A. holes
B. free electrons
C. valence electrons
D. bound electrons

---

181. A hole in a semiconductor is defined as
A. a free electron
B. the incomplete part of an electron pair bond
C. a free proton
D. a free neutron

---

182. The impurity level in an extrinsic semiconductor is about ___ of pure semiconductor.
A. 10 atoms for 108 atoms
B. 1 atom for 108 atoms
C. 1 atom for 104 atoms
D. 1 atom for 100 atoms

---