ASSIGNMENT 12 Textbook Assignment:    "Crash Rescue and Fire Fighting," chapter 12, pages 12-1 through 12-21. 12-1. What is the primary duty of a fire fighter? 1. To prevent fire from spreading 2. To save lives 3. To extinguish fire 4. To protect Navy equipment 12-2. There are four elements in the process of fire. The fourth element is a chemical reaction that allows the fire to sustain itself and grow. Which of the following terms describes this process? 1. Fire triangle 2. Fire cube 3. Fire tetrahedron 4. Fire matrix 12-3. What  is  the  term  used  to  describe  the  lowest temperature at which vapors of a substance can be ignited and continue to burn? 1. Fire point 2. Flash point 3. Ignition point 4. Spark point 12-4. What is the term used to describe the tempera- ture   at   which   a   substance   gives   off   enough vapors to form an ignitable mixture in the air near its surface? 1. Fire point 2. Flash point 3. Ignition point 4. Spark point 12-5. At what exposed temperatures will a portion of fuel (or its vapors) spontaneously ignite? 1. 200°F 2. 300°F 3. 400°F 4. 500°F 12-6. What class of fires occur in combustible mate- rials, such as bedding, mattresses, books, cloth, and any matter that produces an ash? 1. Class A 2. Class B 3. Class C 4. Class D 12-7. What class of fires occur with flammable liq- uid   substances,   such   as   gasoline,   jet   fuels, paints, grease, and any petroleum-based products? 1. Class A 2. Class B 3. Class C 4. Class D 12-8. What class of fires is associated with electric- ally energized equipment? 1. Class A 2. Class B 3. Class C 4. Class D 12-9. What class of fires is associated with combusti- ble metals, such as magnesium and titanium? 1. Class A 2. Class B 3. Class C 4. Class D 12-10.    Water is most efficient when it absorbs enough heat to raise its temperature to a boiling point, and then changes to steam that carries away the heat, which cools the surface temperature. 1. True 2. False 12-11.    When proportioned with water, AFFF provides which    of    the    following    fire-extinguishing advantages? 1. An aqueous film is formed on the surface of the fuel that prevents the escape of the fuel vapors 2. The    layer    effectively    excludes    oxygen from the fuel surface 3. The water content of the foam provides a cooling effect 4. Each of the above 12-23