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CH 1 Self-TestSection 1–12. An atom consists of (d) answers (b) one nucleus and one or more electrons and (c) protons, 4. Valence electrons are (b) in the most distant orbit from the nucleus – Is the correct answer, but Section 1–26. The most widely used semiconductive material in electronic devices is (d) silicon – though germanium is often added (a) germanium8. The energy band in which free electrons exist is the (c) conduction band – “When an electron acquires enough additional energy, it can leave the valence shell, become a free electron, and exist in what is known as the conduction band”[Floyd]. (d) valence band10. The atomic number of silicon is (d) 14 – periodic table #14 Si12. The valence shell in a silicon atom has the number designation of (d) 3 – nucleus plus 3 shells, can be seen in pictures, or on pg 9.Section 1–314. Electron-hole pairs are produced by (b) thermal energy – is what causes valence electrons to jump the gap between bands. Holes are then created and other electrons fill these holes (a) recombination. This normally happens after (d) doping silicon with another element like germanium.16. The current in a semiconductor is produced by (d) both electrons and holes – holes and free electrons create current, unlike in conductors which only have electron current.Section 1–418. The process of adding an impurity to an intrinsic semiconductor is called (a) doping – learned20. The purpose of a pentavalent impurity is to (c) increase the number of free electrons - [Floyd]