24.The flow of valence electrons to the left means that holes are flowing to thea. Leftb. Rightc. Either wayd. None of the aboveb25. Holes act like26. Trivalent atoms have how many valence electrons?27. A donor atom has how many valence electrons?28.If you wanted to produce a p-type semiconductor, which of these would you use?a. Acceptor atomsb. Donor atomsc. Pentavalent impurityd. Silicona29.Holes are the minority carriersin which type of semiconductor?30.How many free electrons does a p-type semiconductor contain?
31.Silver is the best conductor. How many valence electrons do you think it has?32.Suppose an intrinsic semiconductor has 1 billion free electrons at room temperature. If the temperature changes to 75'C, howmany holes are there?a. Fewer than 1 billionb. 1 billionc. More than 1 billiond. Impossible to sayc33.An external voltage source is applied to ap-type semiconductor. If the left end of the crystal is positive, which way do themajority carriers flow?34. Which of the following doesn't fit in the group?35.Which of the following is approximately equal to room temperature?36.How many electrons are there in the valence orbit of a silicon atom within a crystal?a. 1b. 4c. 8d. 14c37. Positive ions are atoms that have38. Which of the following describes an n-type semiconductor?39. A p-type semiconductor contains holes and40. Which of the following describes a p-type semiconductor?a. Neutralb. Positively chargedc. Negatively chargedd. Has many free electronsa41. Which of the following cannot move?42. What causes the depletion layer?