36.  Most commonly employed trivalent impurities are
A. Boron, Indium
B. Arsenic, Antimony
C. Boron, Arsenic
D. Indium, Antimony

---

37.  Most commonly employed pentavalent impurities are
A. Boron, Indium
B. Aluminium, Antimony
C. Arsenic, Indium
D. Arsenic, Antimony

---

38.  A P-type semiconductor material is formed by adding to the semiconductor controlled amounts of
A. some trivalent impurity
B. Some pentavalent impurity
C. arsenic
D. none of these

---

39.  Referring to the energy level diagram of semiconductor materials, the width of forbidden gap is
A. about 10 eV
B. about 100 Ev
C. about 1 eV
D. about 0.1 eV

---

40. A P-type semiconductor material as a whole is
A. positively charged
B. negatively charged
C. electrically neutral
D. none of these

---

41. An N-type semiconductor material as a whole is
A. electrically neutral
B. positively charged
C. negatively charged
D. none of these

---

42. One of the following statements justifies the extensive use of semiconductor materials.
A. It is because of their low forbidden energy gap
B. It is because of their resistance value which lies between that of good conductors and insulator
C. It is because of ease of fabrication of semiconductor material into practical active and passive devices
D. It is because of the fact that they exhibit some wide ranging characteristics when certain specific impurities are added to them in controlled amounts

---